Fixed #12429 -- Ensure that raw queries call resolve_columns if the backend...

Fixed #12429 -- Ensure that raw queries call resolve_columns if the backend defines it. This ensures (as much as possible) that the model values returned by a raw query match that in normal queries. Thanks to Ian Kelly for the report.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@12904 bcc190cf-cafb-0310-a4f2-bffc1f526a37