func_talkdetect: Fix stasis message leak in audiohook callback.

ASTERISK-24482 #close
Reported by: Corey Farrell
Review: https://reviewboard.asterisk.org/r/4142/
........

Merged revisions 427203 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/13@427204 65c4cc65-6c06-0410-ace0-fbb531ad65f3

funcs/func_talkdetect.c

@@ -218,6 +218,7 @@ static int talk_detect_audiohook_cb(struct ast_audiohook *audiohook, struct ast_
 		                blob);
 		if (message) {
 			stasis_publish(ast_channel_topic(chan), message);
+			ao2_ref(message, -1);
 		}
 
 		ast_json_unref(blob);