When possible, sanity check the timezone setting to see if the Unix-like

box it's running on supports that setting. If checking isn't possible,
we skip it. Patch from seveas. Thanks.

Fixed #3415.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@13722 bcc190cf-cafb-0310-a4f2-bffc1f526a37