Configure libpng with "configure --enable-intel-sse" or compile libpng with "-DPNG_INTEL_SSE" in CPPFLAGS to enable it. This patch was previously applied to libpng-1.6.28rc03 but withdrawn to allow time for QA.
Configure libpng with "configure --enable-intel-see" or compile libpng with "-DPNG_INTEL_SSE" in CPPFLAGS to enable it.