Add SET_ALARM permission for SystemUI

If one or more third-party alarm clock app is installed, clicking clock should open an app chooser for the alarm clock. However, permission for com.android.alarm.permission.SET_ALARM is required to make this behaviour work properly.

See http://forum.xda-developers.com/showpost.php?p=33155463&postcount=2749 for symptom if this permission is not assigned.

Change-Id: Iaf8cb9aba6e53da021da5373493b1419096e91fa