audio: SDL_GetAudioStreamQueued now returns bytes, not frames.

Reference #8266.

src/audio/SDL_sysaudio.h

@@ -179,7 +179,7 @@ struct SDL_AudioStream
     float freq_ratio;
 
     struct SDL_AudioQueue* queue;
-    Uint64 total_frames_queued;
+    Uint64 total_bytes_queued;
 
     SDL_AudioSpec input_spec; // The spec of input data currently being processed
     Sint64 resample_offset;