Updated version and CHANGES files with new release number.

Check the API files:
- lib/bind9/api:
  Source code changes, but no interface changes: increment
  LIBREVISION.
- lib/dns/api:
  Function dns_acl_match changed, struct dns_badcache changed,
  function dns_badcache_add changed, function dns_clent_startupdate
  changed, struct dns_compress changed, struct dns_resolver changed,
  rwlock size changed. This means a LIBINTERFACE increment.
- lib/irs/api:
  Source code changes, but no interface changes: increment
  LIBREVISION.
- lib/isc/api:
  The structs isc__networker and isc_nmsocket changed. This means
  increment LIBINTERFACE.  The functions isc_uv_export and
  isc_uv_import are removed, so LIBAGE must beq zero.
- lib/isccc/api:
  Source code changes, but no interface changes: increment
  LIBREVISION.
- lib/isccfg/api:
  Source code changes, but no interface changes: increment
  LIBREVISION.
- lib/ns/api:
  Function ns_clientmgr_create, ns_interfacemgr_create, and
  structs ns_clientmgr, ns_interface, ns_interfacemgr changed:
  increment LIBINTERFACE.

No need to update README or release notes.

Updated CHANGES: Add GitLab MR reference to entry 5357. Remove
merge conflict gone wrong ("max-ixfr-ratio" is not in 9.16).

Add /util/check-make-install.in to .gitattributes.