Add missing pthread_cond_signal

Author: Cuda-Chen

virtio-snd.c

@@ -1013,6 +1013,7 @@ static bool virtio_snd_reg_write(virtio_snd_state_t *vsnd,
             case VSND_QUEUE_TX:
                 fprintf(stderr, "TX start\n");
                 ev_notify++;
+                pthread_cond_signal(&virtio_snd_foo_cond);
                 /*virtio_queue_notify_handler(vsnd, value,
                                             virtio_snd_foo_desc_handler);*/
                 sleep(1);