PulseAudio: force minreq to less than half tlength (refs #7827)

This should work-around distorsion due to excessively short latency
computation in PulseAudio, e.g. NVIDIA HDMI Audio.

In the longer term, VLC should probably set minreq to 40ms and tlength
to a larger value or even -1. But that would require more testing.
(cherry picked from commit a1ddda85bb3cbd7ec4b7bb0aa0fd80c9a6d3afe7)

modules/audio_output/pulse.c

@@ -848,7 +848,7 @@ static int Open(vlc_object_t *obj)
      * TODO? tlength could be adaptively increased to reduce wakeups. */
     attr.tlength = pa_usec_to_bytes(AOUT_MIN_PREPARE_TIME, &ss);
     attr.prebuf = 0; /* trigger manually */
-    attr.minreq = -1;
+    attr.minreq = attr.tlength / 3;
     attr.fragsize = 0; /* not used for output */
 
     /* Allocate structures */