Update to libpng 1.2.52 (rollup change only)

third_party/libpng/README

-README for libpng version 1.2.45 - July 7, 2011 (shared library 12.0)
+README for libpng version 1.2.52 - November 20, 2014 (shared library 12.0)
 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,
 libpng-*.tar.xz, or libpng-*.tar.bz2 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
@@ skipping 74 matching lines @@
 
 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
 
 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.
 
+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
+controls or International Traffic in Arms Regulations (ITAR) because it
+is open source, publicly available software, that does not contain any
+encryption software.  See the EAR, paragraphs 734.3(b)(3) and 734.7(b).
+
 If you have any code changes, requests, problems, etc., please e-mail
 them to me.  Also, I'd appreciate any make files or project files,
 and any modifications you needed to make to get libpng to compile,
 along with a #define variable to tell what compiler/system you are on.
 If you needed to add transformations to libpng, or wish libpng would
 provide the image in a different way, drop me a note (and code, if
 possible), so I can consider supporting the transformation.
 Finally, if you get any warning messages when compiling libpng
 (note: not zlib), and they are easy to fix, I'd appreciate the
 fix.  Please mention "libpng" somewhere in the subject line.  Thanks.
@@ skipping 16 matching lines @@
 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
 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
 to others, if necessary.
 
 Please do not send suggestions on how to change PNG.  We have
-been discussing PNG for twelve years now, and it is official and
+been discussing PNG for nineteen years now, and it is official and
 finished.  If you have suggestions for libpng, however, I'll
 gladly listen.  Even if your suggestion is not used immediately,
 it may be used later.
 
 Files in this distribution:
 
       ANNOUNCE      =>  Announcement of this version, with recent changes
       CHANGES       =>  Description of changes between libpng versions
       KNOWNBUG      =>  List of known bugs and deficiencies
       LICENSE       =>  License to use and redistribute libpng
@@ skipping 24 matching lines @@
       pngtest.png   =>  Library test sample image
       pngtrans.c    =>  Common data transformation functions
       pngwio.c      =>  Lowest-level write I/O functions
       pngwrite.c    =>  High-level write functions
       pngwtran.c    =>  Write data transformations
       pngwutil.c    =>  Write utility functions
       contrib       =>  Contributions
        gregbook         =>  source code for PNG reading and writing, from
                             Greg Roelofs' "PNG: The Definitive Guide",
                             O'Reilly, 1999
-       msvctest     =>  Builds and runs pngtest using a MSVC workspace
-       pngminim     =>  Simple pnm2pngm and png2pnmm programs
+       pngminim     =>  Minimal pnm2pngm and png2pnmm programs
        pngminus     =>  Simple pnm2png and png2pnm programs
        pngsuite     =>  Test images
        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
+       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
       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.0.1.2.45)
+                            creates libpng12.so.0.1.2.52)
        makefile.linux   =>  Linux/ELF makefile (gcc, creates
-                            libpng12.so.0.1.2.45)
+                            libpng12.so.0.1.2.52)
        makefile.gcmmx   =>  Linux/ELF makefile (gcc, creates
-                            libpng12.so.0.1.2.45, previously
+                            libpng12.so.0.1.2.52, 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.0.1.2.45)
+                            (gcc, creates libpng12.so.0.1.2.52)
        makefile.sunos   =>  Sun makefile
        makefile.solaris =>  Solaris 2.X makefile
-                            (gcc, creates libpng12.so.0.1.2.45)
+                            (gcc, creates libpng12.so.0.1.2.52)
        makefile.so9     =>  Solaris 9 makefile
-                            (gcc, creates libpng12.so.0.1.2.45)
+                            (gcc, creates libpng12.so.0.1.2.52)
        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
@@ skipping 19 matching lines @@
 -Glenn Randers-Pehrson (current maintainer, since 1998)
  Internet: glennrp at users.sourceforge.net
 
 -Andreas Eric Dilger (former maintainer, 1996-1997)
  Internet: adilger at enel.ucalgary.ca
  Web: http://members.shaw.ca/adilger/
 
 -Guy Eric Schalnat (original author and former maintainer, 1995-1996)
  (formerly of Group 42, Inc)
  Internet: gschal at infinet.com