server: Ensure we flush the release pipe after an oom

We really need to flush the ring to ensure that we push something on the
release ring. If we don't do this and the ring is not pushed for other
reasons we will timeout in the guest driver waiting for the ring.

server/red_worker.c

@@ -9951,6 +9951,7 @@ static void handle_dev_input(EventListener *listener, uint32_t events)
             red_printf("oom current %u pipe %u", worker->current_size, worker->display_channel ?
                        worker->display_channel->base.pipe_size : 0);
             red_free_some(worker);
+            worker->qxl->st->qif->flush_resources(worker->qxl);
         }
         clear_bit(RED_WORKER_PENDING_OOM, worker->pending);
         break;