arm: Fix VarHandle.compareAndSet() with read barriers.

A stress test shall be added in separate change,
    https://android-review.googlesource.com/2003811 .

Test: testrunner.py --target --32 --optimizing
Bug: 208156527
Change-Id: I9d5f122235a27b6ab629e187afbc3e2f5d4a75ce
1 file changed