Fix unchecked return value in krb5 common utils

https://fedorahosted.org/freeipa/ticket/4713

Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>

util/ipa_krb5.c

@@ -730,6 +730,10 @@ struct berval *create_key_control(struct keys_container *keys,
 
         if (ksdata[i].salttype == NO_SALT) {
             ret = ber_printf(be, "}");
+            if (ret == -1) {
+                ber_free(be, 1);
+                return NULL;
+            }
             continue;
         }