NSS: Better handle ERR_NO_TS in sysdb_enumpwent_filter()

Although ts_res.count is set to 0 when sysdb_search_ts_users()
return ERR_NO_TS, before using it we make an extra check to verify
that the returned code is EOK.

Reviewed-by: Alexey Tikhonov <atikhono@redhat.com>
Reviewed-by: Sumit Bose <sbose@redhat.com>
(cherry picked from commit 0a739f8)

Author: aplopez

src/db/sysdb_search.c

@@ -899,7 +899,7 @@ int sysdb_enumpwent_filter(TALLOC_CTX *mem_ctx,
             goto done;
         }
 
-        if (ts_res.count > 0) {
+        if (ret == EOK && ts_res.count > 0) {
             ret = sysdb_enum_dn_filter(tmp_ctx, &ts_res, attr_filter, domain->name,
                                        &dn_filter);
             if (ret != EOK) {