Resolve a ref leak in threadpool.c

Ownership of the listener reference is not transferred because the
listener is reffed when placed into the taskprocessor. Ensure that the
listener is dereffed properly.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@382489 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/threadpool.c

@@ -1188,7 +1188,6 @@ struct ast_taskprocessor *ast_threadpool_serializer(const char *name, struct ast
 	if (!tps) {
 		return NULL;
 	}
-	listener = NULL; /* ownership transferred to tps */
 
 	return tps;
 }