CLSA-2026-1779494089 Fix of 7 CVEs

SECURITY UPDATE: PostgreSQL 2026-05-14 security batch CVE-2026-6473, 6474, 6475, 6477, 6478, 6479, 6637. Backports adapted from upstream REL14STABLE to PG 12 source. - debian/patches/CVE-2026-6473.patch: integer wraparound in tsheadline and ltree lquery parsing; bound...