Fix an issue with trying to kill a thread before it gets created.

Issue 9709, patch by nic_bellamy.


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.2@63828 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_iax2.c

@@ -2563,7 +2563,8 @@ static int iax2_transmit(struct iax_frame *fr)
 	iaxq.count++;
 	ast_mutex_unlock(&iaxq.lock);
 	/* Wake up the network thread */
-	pthread_kill(netthreadid, SIGURG);
+	if (netthreadid != AST_PTHREADT_NULL)
+		pthread_kill(netthreadid, SIGURG);
 	return 0;
 }