player: exit if audio init fails and there's no video

Seems logical. For some reason, the player allows deselecting both audio
and video stream without quitting (a deliberate feature of which I have
no idea why it was added years ago), so this is needed.

player/audio.c

@@ -288,6 +288,8 @@ no_audio:
     mp_deselect_track(mpctx, track);
     if (track)
         MP_INFO(mpctx, "Audio: no audio\n");
+    if (!mpctx->current_track[STREAM_VIDEO])
+        mpctx->stop_play = PT_NEXT_ENTRY;
 }
 
 // Return pts value corresponding to the end point of audio written to the