Use queued audio duration instead of queued frame count to constrain latency

This avoids latency explosion when we negotiate 10 ms instead of 5 ms audio packets.

app/streaming/audio/renderers/sdl.h

@@ -21,5 +21,6 @@ public:
 private:
     SDL_AudioDeviceID m_AudioDevice;
     void* m_AudioBuffer;
-    int m_FrameSize;
+    Uint32 m_FrameSize;
+    Uint32 m_FrameDurationMs;
 };