Version bump libpng to 1.2.50 and switch to the .tar.xz packaging.
Drop patch 200-CVE-2011-3026.patch as it's integrated.
Signed-off-by: Ian Leonard <antonlacon@gmail.com>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
git-svn-id: svn://svn.openwrt.org/openwrt/packages@35794 3c298f89-4303-0410-b956-a3cf2f4a3e73