Add stress test for false-positive comparison in VarHandle CAS.

The new test `$noinline$testAtomicReference()` sometimes
catches the bug fixed by
    https://android-review.googlesource.com/2004080 .
With the fix reverted, it was hit 3/100 times with other
tests commented out and 5/100 with other tests included.

Test: 183-rmw-stress-test
Bug: 218453177
Change-Id: I4dcaba9d145fb48a61c43be0e8c2690080c2073c
3 files changed