NSRunLoop getCFRunLoop incorrect

Currently is:

``` objc
/**
 @Status Interoperable
 @Notes CFRunLoop and NSRunLoop are the same object.  Returns self.
*/
- (CFRunLoopRef)getCFRunLoop {
    return static_cast<CFRunLoopRef>(self);
}
```

But NSRunLoop is not built on CFRunLoop so the returned value is _not_ a valid CFRunLoop
