nss: Raise exception earlier on unsupported DB type
For now FreeIPA handles explicit migration of NSS DB (dbm->sql).
But Mozilla's NSS can be built without the support of legacy database
(DBM). This implies that neither implicit nor explicit DB migration
to SQL will work. So, eventually, this support will be removed from
FreeIPA.
With this patch, the instantiation of NSS with legacy db(if not
supported by NSS) is forbidden.
Fixes: https://pagure.io/freeipa/issue/8474
Signed-off-by: Stanislav Levin <slev@altlinux.org>
Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>