Support field VarHandle objects in boot image.

Test: Build with WIP changes to implement AtomicInteger with
      VarHandle. Build succeeds.
Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Bug: 191765508
Change-Id: I084ab7b3cd082570a090f3470fdfb792b80f4505
6 files changed