test: make test-http-unix-socket use common.PIPE

Don't unlink the socket, that's the responsibility of libuv and/or node.

test/simple/test-http-unix-socket.js

@@ -24,8 +24,6 @@ var assert = require('assert');
 var fs = require('fs');
 var http = require('http');
 
-var SOCKET = common.tmpDir + '/http.sock';
-
 var status_ok  = false; // status code == 200?
 var headers_ok = false;
 var body_ok    = false;
@@ -39,10 +37,10 @@ var server = http.createServer(function(req, res) {
   res.end();
 });
 
-server.listen(SOCKET, function() {
+server.listen(common.PIPE, function() {
 
   var options = {
-    socketPath: SOCKET,
+    socketPath: common.PIPE,
     path: '/'
   };
 
@@ -76,12 +74,6 @@ server.listen(SOCKET, function() {
 
 });
 
-server.on('close', function() {
-  try {
-    fs.unlinkSync(SOCKET);
-  } catch (e) {}
-});
-
 process.on('exit', function() {
   server.close();
   assert.ok(status_ok);