fix node 0.12 warning about customFds

node_modules/vfs-child/parent.js

@@ -15,7 +15,7 @@ function Parent(fsOptions) {
         options.uid = fsOptions.uid;
         delete fsOptions.uid;
     }
-    options.customFds = [-1, -1, 2];
+    options.stdio = options.customFds = [-1, -1, 2];
     var args = [require.resolve('./child.js'), JSON.stringify(fsOptions)];
     var executablePath = process.execPath;
     var child;