Verify external CA's basic constraint pathlen
IPA no verifies that intermediate certs of external CAs have a basic
constraint path len of at least 1 and increasing.
Fixes: https://pagure.io/freeipa/issue/7877
Signed-off-by: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Fraser Tweedale <ftweedal@redhat.com>
Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>