PulseAudio: adjust overall latency, not (only) the buffer size

Without this flag, PulseAudio will tweak the buffer parameters, but
will not account for hardware latencies. As a consequence, the live
caching parameter is not really followed - the latency is longer.

Longer latency becomes a big problem when trying to synch with another
live source (such as a V4L2 video capture device). Then audio is too
late and gets discarded or messed up at output.
(cherry picked from commit d8a96604)

modules/access/pulse.c

@@ -287,6 +287,7 @@ static int Open(vlc_object_t *obj)
 
     const pa_stream_flags_t flags = PA_STREAM_INTERPOLATE_TIMING
                                   | PA_STREAM_AUTO_TIMING_UPDATE
+                                  | PA_STREAM_ADJUST_LATENCY
                                   | PA_STREAM_FIX_FORMAT
                                   | PA_STREAM_FIX_RATE
                                   /*| PA_STREAM_FIX_CHANNELS*/;