Removed some checks for Model._meta.one_to_one_field to prevent list_filter...

Removed some checks for Model._meta.one_to_one_field to prevent list_filter and the show_result_count in search_form.html. Fixes #2145.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@8388 bcc190cf-cafb-0310-a4f2-bffc1f526a37