Fix alarm wakelock not being released.

Alarm wakelock was not released when the pending intent was served
by the package with a uid not the same as the one which created the
alarm.
Remove advanced for loop from PowerManagerService since the list is
modified during iteration and thus resulting to
ConcurrentModificationException error

Change-Id: I4e2ff1f4be1ad044aa350886a3ea69ee5a576f74
CRs-Fixed: 591170
CRs-Fixed: 591511