Binder cache for hasSystemFeature().

System features are build-time constants, so the cache is invalidated only
when the system server restarts.

Bug: 140788621

Test: A special build that puts the PropertyInvalidatedCache in
verification mode was loaded on the device.  Then one iteration of MPTS was
executed.  No cache inconsistencies were found and no SELinux violations
(associated with the binder cache) were found.  The number of cache misses
was approximately 15% of the total binder calls.  98.5% of all binder calls
went through the cache.

Change-Id: Icd23283512ab648ed589d461d2a86e1c3807b45a