Confbridge channels staying active when all participants leave.

If you started/stopped recording of a conference multiple times channels
would remain active even when all participants left the conference.  This
was due to the fact that a reference to the confbridge was being added
every time a start record command was issued, but when the recording was
stopped there was no matching de-reference thus keeping the conference alive.
Made sure only a single reference is added for the record thread no matter how
many times recording is started/stopped.  A de-reference is issued upon thread
ending.

Note, this issue is being fixed under AST-1088 since it relates to it and
should have been corrected along with those modifications.

(issue AST-1088)
Reported by: John Bigelow
........

Merged revisions 381737 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@381741 65c4cc65-6c06-0410-ace0-fbb531ad65f3

apps/app_confbridge.c

@@ -775,8 +775,6 @@ static int conf_start_record(struct conference_bridge *conference_bridge)
  */
 static int start_conf_record_thread(struct conference_bridge *conference_bridge)
 {
-	ao2_ref(conference_bridge, +1); /* give the record thread a ref */
-
 	conf_start_record(conference_bridge);
 
 	/*
@@ -786,6 +784,8 @@ static int start_conf_record_thread(struct conference_bridge *conference_bridge)
 		return 0;
 	}
 
+	ao2_ref(conference_bridge, +1); /* give the record thread a ref */
+
 	if (ast_pthread_create_background(&conference_bridge->record_thread, NULL, record_thread, conference_bridge)) {
 		ast_log(LOG_WARNING, "Failed to create recording channel for conference %s\n", conference_bridge->name);
 		ao2_ref(conference_bridge, -1); /* error so remove ref */