Fix wide volatile IGET/IPUT on ARM without atomic ldrd/strd.

If ldrd/strd isn't atomic, IPUT_WIDE uses ldrexd+strexd and
we need to record the safepoint for the ldrexd rather than
strexd. IGET_WIDE was simply missing the memory barrier.

Bug: 18993519
Change-Id: I4e9270b994f413c1a047c1c4bb9cce5f29e42cb4
3 files changed