png_get_header_ver  684 3rdparty/libpng/png.c    return png_get_header_ver(png_ptr);
png_get_header_ver  501 3rdparty/libpng/png.h #define png_libpng_ver png_get_header_ver(NULL)
png_get_header_ver 2392 3rdparty/libpng/png.h PNG_EXPORT(181, png_const_charp, png_get_header_ver,