[libpng15] Updated scripts/makefile.msys, options.awk, and vers.dfn
[libpng15] Fix 'setting' handling in options.awk and fixed palette_max API
[libpng15] Imported from libpng-1.5.15beta02.tar
[libpng15] Bump version to 1.5.15beta03
[libpng15] Turn serial tests back on (recently turned off by autotools upgrade).
[libpng15] Imported from libpng-1.5.15beta03.tar
[libpng15] Bump version to 1.5.15beta04
[libpng15] Updated man page about png_get_palette_max().
Merge remote-tracking branch 'origin/libpng15' into libpng15-ssse3