third_party/libpng: update to 1.2.54

third_party/libpng/README

Index: third_party/libpng/README
diff --git a/third_party/libpng/README b/third_party/libpng/README
index 4b49627bb478d20a11fc91b0cd922785a078d098..0c8ca72a9df01e271c5165b0a89dfde32c6f7a3c 100644
--- a/third_party/libpng/README
+++ b/third_party/libpng/README
@@ -1,4 +1,4 @@
-README for libpng version 1.2.52 - November 20, 2014 (shared library 12.0)
+README for libpng version 1.2.54 - November 12, 2015 (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.
@@ -135,7 +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 nineteen years now, and it is official and
+been discussing PNG for twenty 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.
@@ -207,11 +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.0.1.2.52)
+                            creates libpng12.so.0.1.2.54)
        makefile.linux   =>  Linux/ELF makefile (gcc, creates
-                            libpng12.so.0.1.2.52)
+                            libpng12.so.0.1.2.54)
        makefile.gcmmx   =>  Linux/ELF makefile (gcc, creates
-                            libpng12.so.0.1.2.52, previously
+                            libpng12.so.0.1.2.54, previously
                             used assembler code tuned for Intel MMX
                             platform)
        makefile.gcc     =>  Generic makefile (gcc, creates static
@@ -236,12 +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.0.1.2.52)
+                            (gcc, creates libpng12.so.0.1.2.54)
        makefile.sunos   =>  Sun makefile
        makefile.solaris =>  Solaris 2.X makefile
-                            (gcc, creates libpng12.so.0.1.2.52)
+                            (gcc, creates libpng12.so.0.1.2.54)
        makefile.so9     =>  Solaris 9 makefile
-                            (gcc, creates libpng12.so.0.1.2.52)
+                            (gcc, creates libpng12.so.0.1.2.54)
        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