test: avoid connecting to :: in test-net-timeout

This test tries to connect to :: or 0.0.0.0, which resolves to localhost
on some platforms but not others. Change to specify localhost.

test/gc/test-net-timeout.js

@@ -1,4 +1,5 @@
 'use strict';
+const common = require('../common');
 // just like test/gc/http-client-timeout.js,
 // but using a net server/client instead
 
@@ -19,7 +20,6 @@ function serverHandler(sock) {
 
 const net = require('net');
 const weak = require('weak');
-require('../common');
 const assert = require('assert');
 const todo = 500;
 let done = 0;
@@ -29,7 +29,7 @@ let countGC = 0;
 console.log('We should do ' + todo + ' requests');
 
 var server = net.createServer(serverHandler);
-server.listen(0, getall);
+server.listen(0, common.localhostIPv4, getall);
 
 function getall() {
   if (count >= todo)