Fixed #9568 -- Hide nav-global div in admin login template in case it's used...

Fixed #9568 -- Hide nav-global div in admin login template in case it's used admin/base_site.html or admin/base.html. Thanks, AmanKow.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@14766 bcc190cf-cafb-0310-a4f2-bffc1f526a37