Update libpng to version 1.2.44

third_party/libpng/png.h

 /* png.h - header file for PNG reference library
  *
  * libpng version 1.2.43 - February 25, 2010
  * Copyright (c) 1998-2010 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
  * This code is released under the libpng license (See LICENSE, below)
  *
  * Authors and maintainers:
@@ skipping 241 matching lines @@
  *    1.2.41                  13    10241  12.so.0.41[.0]
  *    1.2.42beta01-02         13    10242  12.so.0.42[.0]
  *    1.2.42rc01-05           13    10242  12.so.0.42[.0]
  *    1.0.52                  10    10052  10.so.0.52[.0]
  *    1.2.42                  13    10242  12.so.0.42[.0]
  *    1.2.43beta01-05         13    10243  12.so.0.43[.0]
  *    1.0.53rc01-02           10    10053  10.so.0.53[.0]
  *    1.2.43rc01-02           13    10243  12.so.0.43[.0]
  *    1.0.53                  10    10053  10.so.0.53[.0]
  *    1.2.43                  13    10243  12.so.0.43[.0]
+ *    1.2.44beta01-03         13    10244  12.so.0.44[.0]
+ *    1.2.44rc01-03           13    10244  12.so.0.44[.0]
+ *    1.2.44                  13    10244  12.so.0.44[.0]
  *
  *    Henceforth the source version will match the shared-library major
  *    and minor numbers; the shared-library major version number will be
  *    used for changes in backward compatibility, as it is intended.  The
  *    PNG_LIBPNG_VER macro, which is not used within libpng but is available
  *    for applications, is an unsigned integer of the form xyyzz corresponding
  *    to the source version x.y.z (leading zeros in y and z).  Beta versions
  *    were given the previous public release number plus a letter, until
  *    version 1.0.6j; from then on they were given the upcoming public
  *    release number plus "betaNN" or "rcNN".
@@ skipping 3504 matching lines @@
 
 #endif /* PNG_INTERNAL */
 
 #ifdef __cplusplus
 }
 #endif
 
 #endif /* PNG_VERSION_INFO_ONLY */
 /* Do not put anything past this line */
 #endif /* PNG_H */