libpng was updated to fix some security issues:
CVE-2014-9495 [bnc#912076]: Heap-buffer overflow png_combine_row() with
very wide interlaced images
CVE-2015-0973 [bnc#912929]: overflow in png_read_IDAT_data
libpng is now also build with -DPNG_SAFE_LIMITS_SUPPORTED.