Add FIPS mode enabled builds to GitLab CI

BIND9 supports FIPS mode (--enable-fips-mode) but is not regularly tested in the CI. For this to happen this needs to be accomplished:

Basic FIPS build fixes integrated !4281 (performs builds with --enable-fips-mode)
System test can run without MD5 (there's plenty of algorithm hmac-md5; in system test or implicit expectation of MD5 in dig invocations in acl and allow-query system tests)
Red Hat FIPS patches by @pemensik at https://src.fedoraproject.org/rpms/bind/tree/master for v9_11 evaluated
FIPS-enabled host or VM image (most likely with CentOS)
CI job(s) with --enable-fips-mode in the build stage and subsequent unit and system test CI jobs