Added default case with error for object event dispatching

Hitting this should be pretty rare, but at least developers will know
that they are providing a weird event ID. Otherwise for namespace that
are added in the normal way, gcc will raise a warning about unhandled
case in the switch.

src/conf/object_event.c

@@ -646,6 +646,8 @@ virObjectEventStateDispatchFunc(virConnectPtr conn,
         virNetworkEventDispatchDefaultFunc(conn, event,
                 VIR_NETWORK_EVENT_CALLBACK(cb), cbopaque, NULL);
         break;
+    default:
+        VIR_ERROR(_("Unknown event namespace to dispatch"));
     }
     virObjectEventStateLock(state);
 }