Log Message:
Update to 1.2.43:

version 1.2.42beta01 [December 4, 2009]
  Removed "#define PNG_NO_ERROR_NUMBERS" that was inadvertently added
    to pngconf.h in version 1.2.41.
  Revised scripts/makefile.netbsd, makefile.openbsd, and makefile.sco
    to put png.h and pngconf.h in $prefix/include, like the other scripts,
    instead of in $prefix/include/libpng.  Also revised makefile.sco
    to put them in $prefix/include/libpng12 instead of in
    $prefix/include/libpng/libpng12.
  Removed leftover "-DPNG_CONFIGURE_LIBPNG" from scripts/makefile.darwin

version 1.2.42beta02 [December 11, 2009]
  Removed leftover "-DPNG_CONFIGURE_LIBPNG" from \ 
contrib/pngminim/*/makefile
  Relocated png_do_chop() to its original position in pngrtran.c. The
    change in version 1.2.41beta08 caused transparency to be handled wrong
    in some 16-bit datastreams (Yusaku Sugai).

version 1.2.42rc01 [December 17, 2009]
  No changes.

version 1.2.42rc02 [December 22, 2009]
  Renamed libpng-pc.in back to libpng.pc.in and revised CMakeLists.txt
    (revising changes made in 1.2.41beta17 and 1.2.41rc01)

version 1.2.42rc03 [December 25, 2009]
  Swapped PNG_UNKNOWN_CHUNKS_SUPPORTED and PNG_HANDLE_AS_UNKNOWN_SUPPORTED
    in pngset.c to be consistent with other changes in version 1.2.38.

version 1.2.42rc04 [January 1, 2010]
  Marked png_memcpy_check() and png_memset_check() PNG_DEPRECATED.
  Updated copyright year.

version 1.2.42rc05 [January 2, 2010]
  Avoid deprecated references to png_ptr-io_ptr and png_ptr->error_ptr
    in pngtest.c

version 1.2.42 and 1.0.52 [January 3, 2010]
  No changes.

version 1.2.43beta01 [January 27, 2010]
  Updated CMakeLists.txt for consistent indentation and to avoid an
    unclosed if-statement warning (Philip Lowman).
  Removed "#ifdef PNG_1_0_X / #endif" surrounding
    PNG_READ_16_TO_8_SUPPORTED and PNG_READ_GRAY_TO_RGB_SUPPORTED
    in pngconf.h.  These were added in libpng-1.2.41beta08 and libpng-1.0.51,
    which introduced a binary incompatibility with libpng-1.0.50.
  Backported new png_decompress_chunk() algorithm from libpng-1.4.1.

version 1.2.43beta02 [February 1, 2010]
  Backported two-pass png_decompress_chunk() algorithm from libpng-1.4.1.

version 1.2.43beta03 [February 6, 2010]
  Backported fast png_push_save_buffer() algorithm from libpng-1.4.1.
  Backported some cosmetic changes from libpng-1.4.1.

version 1.2.43beta04 [February 8, 2010]
  Reverted recent changes to png_push_save-buffer().
  Removed PNGAPI declaration of png_calloc() and png_write_sig() in
    1ibpng-1.2.X, introduced by mistake in libpng-1.2.41.
  Return allocated "old_buffer" in png_push_save_buffer() before \ 
png_error()
    to avoid a potential memory leak.

version 1.2.43beta05 [February 8, 2010]
  Ported rewritten png_decompress_chunk() by John Bowler from libpng-1.4.1.

version 1.0.53rc01 and 1.2.43rc01 [February 18, 2010]
  No changes.

version 1.0.53rc02 and 1.2.43rc02 [February 19, 2010]
  Define _ALL_SOURCE in configure.ac, makefile.aix, and CMakeLists.txt
    when using AIX compiler.

version 1.0.53 and 1.2.43 [February 25, 2010]
  Removed unused gzio.c from contrib/pngminim gather and makefile scripts