Update to libpng 1.2.52 (rollup change only)

third_party/libpng/README

Index: third_party/libpng/README
diff --git a/third_party/libpng/README b/third_party/libpng/README
index 8d017db2e7b6c91c528ad46d7fe5449b3945509d..4b49627bb478d20a11fc91b0cd922785a078d098 100644
--- a/third_party/libpng/README
+++ b/third_party/libpng/README
@@ -1,4 +1,4 @@
-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.
@@ -93,6 +93,12 @@ This code is currently being archived at libpng.sf.net in the
 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,
@@ -129,7 +135,7 @@ 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.
@@ -174,8 +180,7 @@ Files in this distribution:
        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
@@ -184,11 +189,14 @@ Files in this distribution:
        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
@@ -199,11 +207,11 @@ Files in this distribution:
        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
@@ -228,12 +236,12 @@ Files in this distribution:
        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