Fix joinable thread terminating without joiner memory leak in chan_iax.c.

The iax2_process_thread() can exit without anyone waiting to join the
thread.  If noone is waiting to join the thread then a large memory leak
occurs.

* Made iax2_process_thread() deatach itself if nobody is waiting to join
the thread.

(closes issue ASTERISK-17339)
Reported by: Tzafrir Cohen
Patches:
      asterisk-1.8.4.4-chan_iax2-detach-thread-on-non-stop-exit.patch (license #5617) patch uploaded by Alex Villacis Lasso (modified)

(closes issue ASTERISK-17825)
Reported by: wangjin
........

Merged revisions 350220 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 350221 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@350222 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_iax2.c

@@ -11839,7 +11839,8 @@ static void *iax2_process_thread(void *data)
 		handle_deferred_full_frames(thread);
 	}
 
-	/*!\note For some reason, idle threads are exiting without being removed
+	/*!
+	 * \note For some reason, idle threads are exiting without being removed
 	 * from an idle list, which is causing memory corruption.  Forcibly remove
 	 * it from the list, if it's there.
 	 */
@@ -11851,6 +11852,11 @@ static void *iax2_process_thread(void *data)
 	AST_LIST_REMOVE(&dynamic_list, thread, list);
 	AST_LIST_UNLOCK(&dynamic_list);
 
+	if (!thread->stop) {
+		/* Nobody asked me to stop so nobody is waiting to join me. */
+		pthread_detach(pthread_self());
+	}
+
 	/* I am exiting here on my own volition, I need to clean up my own data structures
 	* Assume that I am no longer in any of the lists (idle, active, or dynamic)
 	*/