How do I filter by date is null in a View I have a View of contacts including the date of birth and want to filter by the date not being set.  When I add a filter on the date it provides a range of options (greater than, less than etc), but not one for "is null".

How can I add that?  Is there some configuration or another module to provide this functionality?
I do not know the answer, but did a quick Google: https://www.drupal.org/node/2107633
I would recommend you ask the question on the Drupal Stack Exchange site https://drupal.stackexchange.com/ as it is more of a Drupal than a CiviCRM question.