[1.1.X] Fixed #6054: work around PIL's installation brokeness by detecting...

[1.1.X] Fixed #6054: work around PIL's installation brokeness by detecting either of the two ways it can end up being installed.

Backport of [12429] from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.1.X@12430 bcc190cf-cafb-0310-a4f2-bffc1f526a37