[libpng17] Removed more functions that were deprecated in libpng-1.6.0:

  png_malloc_default png_free_default.
  Updated some left over "1.6.0beta32" in code sources.
  Fixed a "png_structp" prototype (should be png_structrp) in arm_init.c
  Updated the version-number hack in pngvalid.c
31 files changed