Add --audio-output-buffer

On some systems, the SDL audio callback is not called frequently enough
(for example it requests 5ms of samples every 10ms), because the output
buffer is too small.

By default, we want to use a small value (5ms) to minimize latency and
buffer underrun, but if it does not work well, users need a way to
increase it.

Refs #3793 <https://github.com/Genymobile/scrcpy/issues/3793>

doc/audio.md

@@ -88,3 +88,14 @@ avoid glitches and smooth the playback:
 ```
 scrcpy --display-buffer=200 --audio-buffer=200
 ```
+
+It is also possible to configure another audio buffer (the audio output buffer),
+by default set to 5ms. Don't change it, unless you get some [robotic and glitchy
+sound][#3793]:
+
+```bash
+# Only if absolutely necessary
+scrcpy --audio-output-buffer=10
+```
+
+[#3793]: https://github.com/Genymobile/scrcpy/issues/3793