They have not been exported to applications since libpng12.

(This is probably unnecessary because it's inside a __GNUC__ block.)

This has been missing since the feature was introduced in libpng-1.6.0beta04.

distributions; it depends on configure, which is not included in those
archives.

ignore all unknown chunks and all known chunks except for IHDR, PLTE, tRNS,
IDAT, and IEND.  Previously it only meant ignore all unknown chunks, the
same as num_chunks == 0. Revised png_image_skip_unused_chunks() to
provide a list of chunks to be processed instead of a list of chunks to
ignore.  Revised contrib/gregbook/readpng2.c accordingly.

replacement with png_convert_to_rfc1123_buffer().

MNG files).

(only update the value when it actually increases, move test for whether
the check is wanted out of the function.

generating the linker mapfile symbol prefix.

The compiler performs an optimization which is safe; however it then warns
about it.  Changing the type of 'palette_number' in pngvalid.c removes the
warning.

on alignment increasing pointer casts when -Wcast-align is passed. This
fixes the cases clang warns about either (pngread.c) by eliminating the
casts from png_bytep to png_uint_16p or, for pngrutil.c where the cast
is previously verified or pngstest.c where it is OK by introducing new
png_aligncast macros to do the cast in a way that clang accepts.

scripts/makefile.freebsd

declaration of png_handle_unknown().

around architecture list; add missing ppc architecture; add architecture
options to shared library link; don't try to create a shared lib based on
missing RELEASE variable (Toby Thain).

Fixes CVE-2011-3048.

    iCCP profile over writing the sRGB chunk, controlled by the
    PNG_sRGB_PROFILE_CHECKS option.