Fix a leak in HasSystemFeatureCache.

Bug: 150037560

Make HasSystemFeatureQuery static so that it does not retain a handle
to ApplicationPackageManager.

Test: Boot with an instrumented image to verify that caching still works
as expected.  Took a heap profile to verify that there were no leaks in
the cache.

Change-Id: I2cd39a6dfab9cc1bf04bb7f55638a572213f04ce