CLSA-2026-1779880647 Fix of 6 CVEs

SECURITY UPDATE: postgresql May-2026 CVE batch - debian/patches/CVE-2026-6473.patch: integer overflow fixes across multiple vulnerable sites: hstoreplperl/hstoreplpython palloc sizing mulsize, arrayagg nitems overflow, intarray/ltxtquery findoprnd left-offset overflow, ltree lquery numvar/totalle...