Patches from Gentoo.
Fix gcc10 -fno-common
libpng patch related to http://www.libpng.org/pub/png/src/libpng-1.2.x-to-1.4.x-summary.txt
Patches from Gentoo.
Fix gcc10 -fno-common
libpng patch related to http://www.libpng.org/pub/png/src/libpng-1.2.x-to-1.4.x-summary.txt