CLSA-2026-1779455055 dnsmasq: Fix of 5 CVEs

CVE-2026-2291: heap OOB write via undersized union bigname buffer - CVE-2026-4890: dnssec NSEC bitmap parsing infinite loop - CVE-2026-4891: dnssec missing rdlen validation in RRSIG records - CVE-2026-4892: helper buffer overflow with large DHCPv6 CLIDs - CVE-2026-4893: broken client subnet...