Backport of CVE-2020-25829 (any-cache-update) to 4.1.x

Backport of CVE-2020-25829 (any-cache-update) to 4.1.x

An issue has been found in PowerDNS Recursor before 4.1.18, 4.2.x before 4.2.5,
and 4.3.x before 4.3.5. A remote attacker can cause the cached records for a
given name to be updated to the Bogus DNSSEC validation state, instead of their
actual DNSSEC Secure state, via a DNS ANY query. This results in a denial of
service for installation that always validate (dnssec=validate), and for
clients requesting validation when on-demand validation is enabled
(dnssec=process).

Origin: https://github.com/PowerDNS/pdns/commit/77409aab0be43071b365760213894d6388c3df30.patch
Bug: https://docs.powerdns.com/recursor/security-advisories/powerdns-advisory-2020-07.html
Bug-Debian: https://bugs.debian.org/972159
Reviewed-by: Daniel Leidert <dleidert@debian.org>
Gbp-Pq: Name CVE-2020-25829.patch