use switch_set_flag in a few places we were doing it manually before

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@10534 d0543943-73ff-0310-b7d9-9358b9ac24b2

src/switch_ivr.c

@@ -50,7 +50,7 @@ SWITCH_DECLARE(switch_status_t) switch_ivr_sleep(switch_core_session_t *session,
 	cng_frame.data = data;
 	cng_frame.datalen = 2;
 	cng_frame.buflen = 2;
-	cng_frame.flags = SFF_CNG;
+	switch_set_flag(&cng_frame, SFF_CNG);
 
 	for (;;) {
 		now = switch_timestamp_now();