Revert "Revert "ART: Start RuntimeCallbacks""

This reverts commit bf6331a45f730e1f1044af2ce43bceda660ae6fc.

Switch to using the mutator lock.

Bug: 31684920
Test: m test-art-host-gtest-runtime_callbacks_test
Test: art/tools/run-jdwp-tests.sh --mode=host --debug
Change-Id: I6ce0f71de2aa9f90cd23cfca7723a793b560b16b
10 files changed