Fix recorder waiting when stream disabled

In the recorder, if the video or audio stream is disabled, do not wait
for its initialization (it will never happen) to process the header.

In that case (scrcpy --no-audio --record=file.mp4), this caused the
whole content to be buffered in memory, and written only on exit.

app/src/recorder.c

@@ -178,9 +178,10 @@ static bool
 sc_recorder_process_header(struct sc_recorder *recorder) {
     sc_mutex_lock(&recorder->mutex);
 
-    while (!recorder->stopped && (!recorder->video_init
-                               || !recorder->audio_init
-                               || sc_recorder_has_empty_queues(recorder))) {
+    while (!recorder->stopped &&
+              ((recorder->video && !recorder->video_init)
+            || (recorder->audio && !recorder->audio_init)
+            || sc_recorder_has_empty_queues(recorder))) {
         sc_cond_wait(&recorder->cond, &recorder->mutex);
     }