CVE-2022-37966 system_mitkrb5: require support for aes enctypes

CVE-2022-37966 system_mitkrb5: require support for aes enctypes

This will never fail as we already require a version that supports aes,
but this makes it clearer.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15237

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
(cherry picked from commit a80f8e1b826ee3f9bbb22752464a73b97c2a612d)
[jsutton@samba.org Fixed conflicts due to missing lib='krb5' argument]