calendar: Privacy Guard support

 * Return an empty MemoryCursor for queries on this provider if the
   calling process has privacy guard enabled.

Change-Id: I9f847924ad147a25d877f5f5e3b43eb5146f6804
Merge branch 'cm-10.1' of https://github.com/CyanogenMod/android_packages_providers_CalendarProvider into DJL10.1