s4-smbtorture: Add test krb5.kdc to prove fix for CVE-2017-11103

BUG: https://bugzilla.samba.org/show_bug.cgi?id=12894

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Garming Sam <garming@catalyst.net.nz>
