* gnu/packages/patches/gd-CVE-2016-5766.patch, gnu/packages/patches/gd-CVE-2016-6128.patch, gnu/packages/patches/gd-CVE-2016-6132.patch, gnu/packages/patches/gd-CVE-2016-6214.patch: New files. * gnu/local.mk (dist_patch_DATA): Add them. * gnu/packages/gd.scm (gd): Use patches.