You may have compiled with zlib.h from zlib-1.2.4 or later but then linked with an...
pngcrush: crash on invalid arguments
Fixed in pngcrush-1.7.69
Because libpng-1.6.11 won't compile on MSVC, I'll skip 1.6.12beta and release libpng-1.6.12rc01...
png.c can't be build as "C" source