fix cpu race on inbound call to pa when no ring file is set

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@9372 d0543943-73ff-0310-b7d9-9358b9ac24b2

src/mod/endpoints/mod_portaudio/mod_portaudio.c

@@ -266,6 +266,8 @@ static switch_status_t channel_on_init(switch_core_session_t *session)
 				if (globals.ring_stream) {
 					WriteAudioStream(globals.ring_stream, abuf, (long) olen, &globals.timer);
 				}
+			} else {
+				switch_yield(10000);
 			}
 		}
 		switch_clear_flag_locked((&globals), GFLAG_RING);