check_keys() has become a trivial wrapper for check_known_keys().
Eliminate it.
This makes its name available. Rename check_known_keys().
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190927134639.4284-24-armbru@redhat.com>