Fix a SEGV in malformed xwd file handler. CVE assignment: http://seclists.org/oss-sec/2016/q2/459 Upstream patches: https://anonscm.debian.org/cgit/collab-maint/imagemagick.git/commit/?h=debian-patches/6.8.9.9-4-for-upstream&id=82a5bbdd47b9b3f43ce3c2aa18741aecc4a0f962 https://anonscm.debian.org/cgit/collab-maint/imagemagick.git/commit/?h=debian-patches/6.8.9.9-4-for-upstream&id=914da276f717b3e21e5af6614887af14af87a9b8