Fix bug in recurrent event dialog picker when setting monthly day of the week.

Bug: 9463328

Dialog picker didn't handle last monthly day of the week. It used 5
instead of -1, whiched caused a crash when syncing with the web and also
having recurrent events not show up on months that didn't have 5 weeks.

Change-Id: Ia32898936a3bcf4b39ff3d0890821d307291755e