Fixes the following security issues:
- CVE-2018-5743: Limiting simultaneous TCP clients is ineffective
https://kb.isc.org/docs/cve-2018-5743
- CVE-2019-6467: An error in the nxdomain redirect feature can cause
BIND to exit with an INSIST assertion failure in query.c
https://kb.isc.org/docs/cve-2019-6467
- CVE-2019-6468: BIND Supported Preview Edition can exit with an
assertion failure if nxdomain-redirect is used
https://kb.isc.org/docs/cve-2019-6468
Add an upstream patch to fix building on architectures where bind does not
implement isc_atomic_*.
Upstream moved to a 2019 signing key, so update comment in .hash file.
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
