require('sys') is deprecated, using 'util' instead

(node:30288) DeprecationWarning: sys is deprecated. Use util instead.

(cherry picked from commit 9a36966 by @travnels)

bench/util/benchwarmer.js

@@ -11,7 +11,7 @@ function BenchWarmer() {
   this.errors = {};
 }
 
-var print = require('sys').print;
+var print = require('util').print;
 
 BenchWarmer.prototype = {
   winners: function(benches) {