CLSA-2026-1789486747 Fix CVE(s): CVE-2026-86421

SECURITY UPDATE: memory leak in the MSL decoder on group end tags - debian/patches/CVE-2026-86421.patch: destroy drawinfo for each grouped image in the group cleanup loop in MSLEndElement in coders/msl.c - debian/patches/CVE-2026-86421-1.patch: bound the group cleanup loop on mslinfo-n in...