FS-4867: --resolve Prevent possible deadlock due to mutexes locked in opposite…

FS-4867: --resolve Prevent possible deadlock due to mutexes locked in opposite order between switch_ivr_dmachine_ping and switch_channel_queue_dtmf

src/switch_core_io.c

@@ -151,7 +151,9 @@ SWITCH_DECLARE(switch_status_t) switch_core_session_read_frame(switch_core_sessi
 	
 	for(i = 0; i < 2; i++) {
 		if (session->dmachine[i] && !switch_channel_test_flag(session->channel, CF_BROADCAST)) {
+			switch_mutex_lock(session->channel->dtmf_mutex);
 			switch_ivr_dmachine_ping(session->dmachine[i], NULL);
+			switch_mutex_unlock(session->channel->dtmf_mutex);
 		}
 	}