- CVE-2017-7948.patch fixes denial of service (integer overflow in mark_curve
function) see https://bugs.ghostscript.com/show_bug.cgi?id=697762
(bsc#1035036)

Please review carefully. Upstream has been working heavily in this area
between 9.21 and the bug fix, so this patch is a backport of the original
fix which required to accept a lot of extra changes into the backport.