Fixed #12230 - Updated utils.translation.to_locale to support the special...

Fixed #12230 - Updated utils.translation.to_locale to support the special sr_Latn locale. Thanks to Janos Guljas.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@12056 bcc190cf-cafb-0310-a4f2-bffc1f526a37