cmp is not by default installed on some containers
(unlike other tools e.g. cut, tr from coreutils or grep).
Also cmp implementation from busybox doesn't support -b, thus detect it.
Signed-off-by: Petr Vorel <pvorel@suse.cz>
Reviewed-by: Bruno Meneguele <bmeneg@redhat.com>(Fedora,CentOS 8(RHEL actually))
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>