Fixed #7033 -- Removed an unused field.

OrderingField was added in the magic-removal branch to support something that
never ultimately materialised, but it wasn't removed. So this is
backwards-incompatible if you're using this field that has no purpose, I guess.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@7794 bcc190cf-cafb-0310-a4f2-bffc1f526a37