Changed django/db/utils.py load_backend() to call sorted() instead of .sort()....

Changed django/db/utils.py load_backend() to call sorted() instead of .sort(). Saves us a line of code. Taken from patch for #15621

git-svn-id: http://code.djangoproject.com/svn/django/trunk@15851 bcc190cf-cafb-0310-a4f2-bffc1f526a37