Use the runtime's implementation for park/unpark

Bug: 28845097
Test: cts-tradefed run cts -m CtsLibcoreTestCases
Test: The following sequence of invocations hangs both before and
      after this CL:
    LockSupport.unpark(Thread.currentThread());
    LockSupport.parkUntil(-1);
    LockSupport.park();

Change-Id: I7ca5d5981d44823c7d6732a59e390dc55927a6ce
3 files changed