Update libpng to 1.6.22

third_party/libpng/README

Index: third_party/libpng/README
diff --git a/third_party/libpng/README b/third_party/libpng/README
index 4f5d4872966d1eb673a03f6607db6661d37dcca6..dc5b52c04886f33c4da1297dec0b1b3048ae8a94 100644
--- a/third_party/libpng/README
+++ b/third_party/libpng/README
@@ -1,15 +1,11 @@
-README for libpng version 1.2.56 - December 17, 2015 (shared library 12.0)
+README for libpng version 1.6.22 - May 26, 2016 (shared library 16.0)
 See the note about version numbers near the top of png.h
 
 See INSTALL for instructions on how to install libpng.
 
 Libpng comes in several distribution formats.  Get libpng-*.tar.gz or
-libpng-*.tar.xz if you want UNIX-style line
-endings in the text files, or lpng*.7z or lpng*.zip if you want DOS-style
-line endings.  You can get UNIX-style line endings from the *.zip file
-by using "unzip -a" but there seems to be no simple way to recover
-UNIX-style line endings from the *.7z file.  The *.tar.xz file is
-recommended for *NIX users instead.
+libpng-*.tar.xz or if you want UNIX-style line endings in the text files,
+or lpng*.7z or lpng*.zip if you want DOS-style line endings.
 
 Version 0.89 was the first official release of libpng.  Don't let the
 fact that it's the first release fool you.  The libpng library has been in
@@ -27,18 +23,25 @@ earlier versions if you are using a shared library.  The type of the
 png_uint_32, which will affect shared-library applications that use
 this function.
 
-To avoid problems with changes to the internals of png_info_struct,
+To avoid problems with changes to the internals of png info_struct,
 new APIs have been made available in 0.95 to avoid direct application
 access to info_ptr.  These functions are the png_set_<chunk> and
 png_get_<chunk> functions.  These functions should be used when
 accessing/storing the info_struct data, rather than manipulating it
 directly, to avoid such problems in the future.
 
-It is important to note that the APIs do not make current programs
+It is important to note that the APIs did not make current programs
 that access the info struct directly incompatible with the new
-library.  However, it is strongly suggested that new programs use
-the new APIs (as shown in example.c and pngtest.c), and older programs
-be converted to the new format, to facilitate upgrades in the future.
+library, through libpng-1.2.x.  In libpng-1.4.x, which was meant to
+be a transitional release, members of the png_struct and the
+info_struct can still be accessed, but the compiler will issue a
+warning about deprecated usage.  Since libpng-1.5.0, direct access
+to these structs is not allowed, and the definitions of the structs
+reside in private pngstruct.h and pnginfo.h header files that are not
+accessible to applications.  It is strongly suggested that new
+programs use the new APIs (as shown in example.c and pngtest.c), and
+older programs be converted to the new format, to facilitate upgrades
+in the future.
 ****
 
 Additions since 0.90 include the ability to compile libpng as a
@@ -58,11 +61,11 @@ to set different actions based on whether the CRC error occurred in a
 critical or an ancillary chunk.
 
 The changes made to the library, and bugs fixed are based on discussions
-on the png-mng-implement mailing list and not on material submitted
+on the PNG-implement mailing list and not on material submitted
 privately to Guy, Andreas, or Glenn.  They will forward any good
 suggestions to the list.
 
-For a detailed description on using libpng, read libpng.txt.  For
+For a detailed description on using libpng, read libpng-manual.txt.  For
 examples of libpng in a program, see example.c and pngtest.c.  For usage
 information and restrictions (what little they are) on libpng, see
 png.h.  For a description on using zlib (the compression library used by
@@ -81,17 +84,15 @@ compression library that is useful for more things than just PNG files.
 You can use zlib as a drop-in replacement for fread() and fwrite() if
 you are so inclined.
 
-zlib should be available at the same place that libpng is, or at
-ftp://ftp.simplesystems.org/pub/png/src/
+zlib should be available at the same place that libpng is, or at zlib.net.
 
 You may also want a copy of the PNG specification.  It is available
 as an RFC, a W3C Recommendation, and an ISO/IEC Standard.  You can find
-these at http://www.libpng.org/pub/png/pngdocs.html
+these at http://www.libpng.org/pub/png/documents/
 
 This code is currently being archived at libpng.sf.net in the
-[DOWNLOAD] area, and on CompuServe, Lib 20 (PNG SUPPORT)
-at GO GRAPHSUP.  If you can't find it in any of those places,
-e-mail me, and I'll help you find it.
+[DOWNLOAD] area, and at ftp://ftp.simplesystems.org.  If you can't find it
+in any of those places, e-mail me, and I'll help you find it.
 
 I am not a lawyer, but I believe that the Export Control Classification
 Number (ECCN) for libpng is EAR99, which means not subject to export
@@ -114,21 +115,19 @@ This release was created and will be supported by myself (of course
 based in a large way on Guy's and Andreas' earlier work), and the PNG
 development group.
 
-Send comments/corrections/commendations to png-mng-implement at lists.sf.net
-(subscription required; visit 
+Send comments/corrections/commendations to png-mng-implement at
+lists.sourceforge.net (subscription required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-implement
 to subscribe) or to glennrp at users.sourceforge.net
 
 You can't reach Guy, the original libpng author, at the addresses
 given in previous versions of this document.  He and Andreas will
-read mail addressed to the png-mng-implement list, however.
+read mail addressed to the png-implement list, however.
 
 Please do not send general questions about PNG.  Send them to
-the (png-mng-misc at lists.sourceforge.net, subscription required, visit
+png-mng-misc at lists.sf.net (subscription required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-misc to
-subscribe). On the other hand, please do not send libpng questions to
-that address, send them to me or to the png-mng-implement list.  I'll
-get them in the end anyway.  If you have a question about something
+subscribe).  If you have a question about something
 in the PNG specification that is related to using libpng, send it
 to me.  Send me any questions that start with "I was using libpng,
 and ...".  If in doubt, send questions to me.  I'll bounce them
@@ -150,14 +149,17 @@ Files in this distribution:
       TODO          =>  Things not implemented in the current library
       Y2KINFO       =>  Statement of Y2K compliance
       example.c     =>  Example code for using libpng functions
-      libpng-*-*-diff.txt => Diff from previous release
-      libpng.3      =>  manual page for libpng (includes libpng.txt)
-      libpng.txt    =>  Description of libpng and its functions
+      libpng.3      =>  manual page for libpng (includes libpng-manual.txt)
+      libpng-manual.txt  =>  Description of libpng and its functions
       libpngpf.3    =>  manual page for libpng's private functions
       png.5         =>  manual page for the PNG format
       png.c         =>  Basic interface functions common to library
-      png.h         =>  Library function and interface declarations
-      pngconf.h     =>  System specific library configuration
+      png.h         =>  Library function and interface declarations (public)
+      pngpriv.h     =>  Library function and interface declarations (private)
+      pngconf.h     =>  System specific library configuration (public)
+      pngstruct.h   =>  png_struct declaration (private)
+      pnginfo.h     =>  png_info struct declaration (private)
+      pngdebug.h    =>  debugging macros (private)
       pngerror.c    =>  Error/warning message I/O functions
       pngget.c      =>  Functions for retrieving info from struct
       pngmem.c      =>  Memory handling functions
@@ -176,98 +178,28 @@ Files in this distribution:
       pngwrite.c    =>  High-level write functions
       pngwtran.c    =>  Write data transformations
       pngwutil.c    =>  Write utility functions
+      arm           =>  Contains optimized code for the ARM platform
       contrib       =>  Contributions
+       examples         =>  Example programs
        gregbook         =>  source code for PNG reading and writing, from
                             Greg Roelofs' "PNG: The Definitive Guide",
                             O'Reilly, 1999
-       pngminim     =>  Minimal pnm2pngm and png2pnmm programs
-       pngminus     =>  Simple pnm2png and png2pnm programs
-       pngsuite     =>  Test images
-       visupng      =>  Contains a MSVC workspace for VisualPng
+       libtests         =>  Test programs
+       pngminim         =>  Minimal decoder, encoder, and progressive decoder
+                            programs demonstrating use of pngusr.dfa
+       pngminus         =>  Simple pnm2png and png2pnm programs
+       pngsuite         =>  Test images
+       tools            =>  Various tools
+       visupng          =>  Contains a MSVC workspace for VisualPng
       projects      =>  Contains project files and workspaces for
                         building a DLL
-       beos             =>  Contains a Beos workspace for building libpng
-       c5builder        =>  Contains a Borland workspace for building
-                            libpng and zlib
-       MacOSX           =>  Contains a MacOSX workspace for building libpng
-       netware.txt      =>  Contains instructions for downloading a set
-                            of project files for building libpng and
-                            zlib on Netware.
-       visualc6         =>  Contains a Microsoft Visual C++ (MSVC)
-                            workspace for building libpng and zlib
+       owatcom          =>  Contains a WATCOM project for building libpng
        visualc71        =>  Contains a Microsoft Visual C++ (MSVC)
                             workspace for building libpng and zlib
-       wince.txt        =>  Contains instructions for downloading a
-                            Microsoft Visual C++ (Windows CD Toolkit)
-                            workspace for building libpng and zlib on
-                            WindowsCE
-       xcode            =>  Contains xcode project files
+       vstudio          =>  Contains a Microsoft Visual C++ (MSVC)
+                            workspace for building libpng and zlib
       scripts       =>  Directory containing scripts for building libpng:
-       descrip.mms      =>  VMS makefile for MMS or MMK
-       makefile.std     =>  Generic UNIX makefile (cc, creates static
-                            libpng.a)
-       makefile.elf     =>  Linux/ELF gcc makefile symbol versioning,
-                            creates libpng12.so.0.1.2.56)
-       makefile.linux   =>  Linux/ELF makefile (gcc, creates
-                            libpng12.so.0.1.2.56)
-       makefile.gcmmx   =>  Linux/ELF makefile (gcc, creates
-                            libpng12.so.0.1.2.56, previously
-                            used assembler code tuned for Intel MMX
-                            platform)
-       makefile.gcc     =>  Generic makefile (gcc, creates static
-                            libpng.a)
-       makefile.knr     =>  Archaic UNIX Makefile that converts files
-                            with ansi2knr (Requires ansi2knr.c from
-                            ftp://ftp.cs.wisc.edu/ghost)
-       makefile.aix     =>  AIX makefile
-       makefile.cygwin  =>  Cygwin/gcc makefile
-       makefile.darwin  =>  Darwin makefile
-       makefile.dec     =>  DEC Alpha UNIX makefile
-       makefile.freebsd =>  FreeBSD makefile
-       makefile.hpgcc   =>  HPUX makefile using gcc
-       makefile.hpux    =>  HPUX (10.20 and 11.00) makefile
-       makefile.hp64    =>  HPUX (10.20 and 11.00) makefile, 64 bit
-       makefile.ibmc    =>  IBM C/C++ version 3.x for Win32 and OS/2
-                            (static)
-       makefile.intel   =>  Intel C/C++ version 4.0 and later
-       libpng.icc       =>  Project file, IBM VisualAge/C++ 4.0 or later
-       makefile.netbsd  =>  NetBSD/cc makefile, makes libpng.so.
-       makefile.ne12bsd  =>  NetBSD/cc makefile, makes libpng12.so
-       makefile.openbsd =>  OpenBSD makefile
-       makefile.sgi     =>  Silicon Graphics IRIX (cc, creates static lib)
-       makefile.sggcc   =>  Silicon Graphics
-                            (gcc, creates libpng12.so.0.1.2.56)
-       makefile.sunos   =>  Sun makefile
-       makefile.solaris =>  Solaris 2.X makefile
-                            (gcc, creates libpng12.so.0.1.2.56)
-       makefile.so9     =>  Solaris 9 makefile
-                            (gcc, creates libpng12.so.0.1.2.56)
-       makefile.32sunu  =>  Sun Ultra 32-bit makefile
-       makefile.64sunu  =>  Sun Ultra 64-bit makefile
-       makefile.sco     =>  For SCO OSr5  ELF and Unixware 7 with Native cc
-       makefile.mips    =>  MIPS makefile
-       makefile.acorn   =>  Acorn makefile
-       makefile.amiga   =>  Amiga makefile
-       smakefile.ppc    =>  AMIGA smakefile for SAS C V6.58/7.00 PPC
-                            compiler (Requires SCOPTIONS, copied from
-                            scripts/SCOPTIONS.ppc)
-       makefile.atari   =>  Atari makefile
-       makefile.beos    =>  BEOS makefile for X86
-       makefile.bor     =>  Borland makefile (uses bcc)
-       makefile.bc32    =>  32-bit Borland C++ (all modules compiled in C mode)
-       makefile.tc3     =>  Turbo C 3.0 makefile
-       makefile.dj2     =>  DJGPP 2 makefile
-       makefile.msc     =>  Microsoft C makefile
-       makefile.vcawin32=>  makefile for Microsoft Visual C++ 5.0 and
-                            later (previously used assembler code tuned
-                            for Intel MMX platform)
-       makefile.vcwin32 =>  makefile for Microsoft Visual C++ 4.0 and
-                            later (does not use assembler code)
-       makefile.os2     =>  OS/2 Makefile (gcc and emx, requires pngos2.def)
-       pngos2.def       =>  OS/2 module definition file used by makefile.os2
-       makefile.watcom  =>  Watcom 10a+ Makefile, 32-bit flat memory model
-       makevms.com      =>  VMS build script
-       SCOPTIONS.ppc    =>  Used with smakefile.ppc
+                            (see scripts/README.txt for the list of scripts)
 
 Good luck, and happy coding.
 
@@ -276,7 +208,7 @@ Good luck, and happy coding.
 
 -Andreas Eric Dilger (former maintainer, 1996-1997)
  Internet: adilger at enel.ucalgary.ca
- Web: http://members.shaw.ca/adilger/
+ Web: http://www-mddsp.enel.ucalgary.ca/People/adilger/
 
 -Guy Eric Schalnat (original author and former maintainer, 1995-1996)
  (formerly of Group 42, Inc)