test: fix test-http-status-reason-invalid-chars

Use port 0 instead of common.PORT, and use server address
instead of localhost to follow writing test guideline.
This is a part of Code And Learn at NodeFest 2016 Challenge in Tokyo.

PR-URL: nodejs#9572
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
Reviewed-By: Shigeki Ohtsu <ohtsu@iij.ad.jp>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: saitoxu

test/parallel/test-http-status-reason-invalid-chars.js

@@ -3,6 +3,7 @@
 const common = require('../common');
 const assert = require('assert');
 const http = require('http');
+const net = require('net');
 
 function explicit(req, res) {
   assert.throws(() => {
@@ -32,8 +33,10 @@ const server = http.createServer((req, res) => {
   } else {
     implicit(req, res);
   }
-}).listen(common.PORT, common.mustCall(() => {
-  const url = `http://localhost:${common.PORT}`;
+}).listen(0, common.mustCall(() => {
+  const addr = server.address().address;
+  const hostname = net.isIPv6(addr) ? `[${addr}1]` : addr;
+  const url = `http://${hostname}:${server.address().port}`;
   let left = 2;
   const check = common.mustCall((res) => {
     left--;