The APNG patch for v1.6.47 isn't out yet, so I hacked in some changes
to get the APNG code to build in pngrutil.c. In particular, the PNGv3
chromacity changes also modified pngrutil.c to use table-based dispatch
instead of an if/else. png_read_frame_head() doesn't use this yet, so
the APNG functions in pngrutil.c haven't been marked static yet, but
they do now return png_handle_result_code.
TODO: Rebase using the APNG patch once it's rebased for v1.6.47.
NOTE: PNGv3 apparently makes APNG part of the specification, so
libpng "should" gain built-in support for APNG without a patch at
some point.
The eXIf functions added in 1.6.31 were broken, so two new functions
were added and the old ones stubbed. This shifts the ordinals for APNG
over by two again.
Note that two new functions were added to the original libpng, so the
ordinals for APNG were shifted over by two. This shouldn't be a problem,
since programs should be accessing functions by name instead of by
ordinal in 2017.
Intel SSE2 was merged into the main codebase.
Added more ARM, MIPS, and PowerPC optimizations, though some of them
aren't currently used by CMakeLists.txt.
I've decided to get rid of the GDI+ PNG handling. It doesn't improve
anything performance-wise, adds coding overhead, and probably isn't
any faster than libpng.
GDI+ also doesn't support APNG. This version does.
NOTE: If I add APNG export, I'll need to use the included libpng
in Ubuntu builds, since Ubuntu still has libpng-1.2, and it's a
version that doesn't support APNG.
Reworked the bundled library system to be similar to the one in
mcrecover, but improved.
Added "-fpic -fPIC" to all extlib static libraries when building
for Linux systems. This is needed for libpng, but might not be
needed for other libraries; nevertheless, it should be set.
TODO: Use libpng in the Windows build. It's being linked in,
but it isn't actually being used for anything yet.
