aout: give volume/mute change a chance after DecPlay (refs #8240)

This is a quick uninvasive work-around for #8240.
A more involved fix is in f788153763bf56fda744df5b9abaa893c402378e.

src/audio_output/dec.c

@@ -29,6 +29,11 @@
 #endif
 
 #include <assert.h>
+#ifdef __unix__
+# include <sched.h>
+#else
+# define sched_yield() (void)0
+#endif
 
 #include <vlc_common.h>
 #include <vlc_aout.h>
@@ -333,6 +338,7 @@ int aout_DecPlay (audio_output_t *p_aout, block_t *p_buffer, int i_input_rate)
     }
 
     aout_unlock( p_aout );
+    sched_yield();
     return 0;
 }