views_date_sql_format function produces wrong date format for postgresql

The views_date_sql_format function in includes/handlers.inc produces the wrong date format for postgresql. The resulting string contains 'YY' (for 2 digit years) and should contain 'YYYY'.

This is exhibited in an unchanged "archive" view, which provides a block containing a list of months. The month names are all displayed the same (the current month), and the links are to archive/0810 instead of archive/200810.

I have included a patch which should fix this issue.