Allow people to set backlog. Need a better API.

lib/net.js

@@ -1187,7 +1187,7 @@ Server.prototype._startWatcher = function () {
 };
 
 Server.prototype._doListen = function () {
-  listen(this.fd, 128);
+  listen(this.fd, this._backlog || 128);
   this._startWatcher();
 };