app_confbridge: Don't play leader leaving prompt if no one will hear it

Consider the following:
- A marked user in a conference
- One or more end_marked only users in the conference

When the marked users leaves, we will be in the conf_state_multi_marked state.
This currently will traverse the users, kicking out any who have the end_marked
flags. When they are kicked, a full ast_bridge_remove is immediately called on
the channels. At this time, we also unilaterally set the need_prompt flag.

When the need_prompt flag is set, we then playback a sound to the bridge
informing everyone that the leader has left; however, no one is left in the
bridge. This causes some odd behaviour for the end_marked users - they are
stuck waiting for the bridge to be unlocked. This results in them waiting for
5 or 6 seconds of dead air before hearing that they've been kicked.

Unfortunately, we do have to keep the bridge locked while we're playing back
the 'leader-has-left' prompt. If there are any wait_marked users in the
conference, this behaviour can't be easily changed - but we do make the case
of the end_marked users better with this patch.

Review: https://reviewboard.asterisk.org/r/4184/

ASTERISK-24522 #close
Reported by: Matt Jordan
........

Merged revisions 428077 from http://svn.asterisk.org/svn/asterisk/branches/11
........

Merged revisions 428078 from http://svn.asterisk.org/svn/asterisk/branches/12
........

Merged revisions 428079 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@428080 65c4cc65-6c06-0410-ace0-fbb531ad65f3

apps/confbridge/conf_state_multi_marked.c

@@ -86,8 +86,6 @@ static void leave_marked(struct confbridge_user *user)
 	conf_remove_user_marked(user->conference, user);
 
 	if (user->conference->markedusers == 0) {
-		need_prompt = 1;
-
 		AST_LIST_TRAVERSE_SAFE_BEGIN(&user->conference->active_list, user_iter, list) {
 			/* Kick ENDMARKED cbu_iters */
 			if (ast_test_flag(&user_iter->u_profile, USER_OPT_ENDMARKED) && !user_iter->kicked) {
@@ -103,6 +101,8 @@ static void leave_marked(struct confbridge_user *user)
 				ast_bridge_remove(user_iter->conference->bridge, user_iter->chan);
 			} else if (ast_test_flag(&user_iter->u_profile, USER_OPT_WAITMARKED)
 				&& !ast_test_flag(&user_iter->u_profile, USER_OPT_MARKEDUSER)) {
+				need_prompt = 1;
+
 				AST_LIST_REMOVE_CURRENT(list);
 				user_iter->conference->activeusers--;
 				AST_LIST_INSERT_TAIL(&user_iter->conference->waiting_list, user_iter, list);