Fixed #3689, #5223 -- Fixed "1st of January" comparisons for SQLite without breaking the other backends.

Based on a patch from raminf and tests from Nebojsa Djordjevic.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@7150 bcc190cf-cafb-0310-a4f2-bffc1f526a37