Log error when update fails

The new "too many records" error can make an update fail without the
error being logged. This commit fixes that.

(cherry picked from commit 558923e5405894cf976d102f0d246a28bdbb400c)

lib/ns/update.c

@@ -3302,9 +3302,18 @@ update_action(isc_task_t *task, isc_event_t *event) {
 						dns_diff_clear(&ctx.add_diff);
 						goto failure;
 					}
-					CHECK(update_one_rr(db, ver, &diff,
-							    DNS_DIFFOP_ADD,
-							    name, ttl, &rdata));
+					result = update_one_rr(
+						db, ver, &diff, DNS_DIFFOP_ADD,
+						name, ttl, &rdata);
+					if (result != ISC_R_SUCCESS) {
+						update_log(client, zone,
+							   LOGLEVEL_PROTOCOL,
+							   "adding an RR "
+							   "failed: %s",
+							   isc_result_totext(
+								   result));
+						goto failure;
+					}
 				}
 			}
 		} else if (update_class == dns_rdataclass_any) {