benchmark: allow empty parameters

PR-URL: https://github.com/nodejs/node/pull/5123
Reviewed-By: Roman Reiss <me@silverwind.io>
Reviewed-By: James M Snell <jasnell@gmail.com>

benchmark/common.js

@@ -188,11 +188,13 @@ function parseOpts(options) {
   var num = keys.length;
   var conf = {};
   for (var i = 2; i < process.argv.length; i++) {
-    var match = process.argv[i].match(/^(.+)=(.+)$/);
+    var match = process.argv[i].match(/^(.+)=(.*)$/);
-    if (!match || !match[1] || !match[2] || !options[match[1]]) {
+    if (!match || !match[1] || !options[match[1]]) {
       return null;
     } else {
-      conf[match[1]] = isFinite(match[2]) ? +match[2] : match[2]
+      conf[match[1]] = (match[2].length && isFinite(match[2])
+                        ? +match[2]
+                        : match[2]);
       num--;
     }
   }