Disable the UnsafeCASObject intrinsic with read barriers.

The current implementations of the UnsafeCASObject
intrinsics are missing a read barrier.  Temporarily disable
them when read barriers are enabled.

Also re-enable the jsr166.LinkedTransferQueueTest tests that
were failing on the concurrent collector configuration, as
the UnsafeCASObject JNI implementation now correctly
implements the read barrier which was missing.

Bug: 25883050
Bug: 26205973
Change-Id: Iaf5d515532949662d0ac6702c9452a00aa0a23e6