Log Message:
patch: Backport patches for several security fixes

pkgsrc changes:
 - Remove custom and no longer needed do-patch target, it was fixed upstream
 - Minor cosmetic improvements pointed out by pkglint

Changes:
 - Backport patches for CVE-2018-6951, CVE-2018-6952 and CVE-2018-1000156

Patch provided by Attila Fülöp via NetBSD/pkgsrc#33, thanks!

Bump PKGREVISION