[AC-2824] iPhone commonjs modules shouldnt copy references out of exports

exports.my_overridable_function = function() {...} // replace this with your own functionality 
exports.do_stuff = function() { exports.my_overridable_function(foo); do_more_stuff_with(foo); return foo; };

var mymodule = require('mymodule');
mymodule.my_overridable_function = function() { ... };

// this wont call my function because the module object isnt the real exports object. 
mymodule.do_stuff();