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
diff --git a/compiler/optimizing/intrinsics_mips64.cc b/compiler/optimizing/intrinsics_mips64.cc
index 8aa7d9f..8b45ea7 100644
--- a/compiler/optimizing/intrinsics_mips64.cc
+++ b/compiler/optimizing/intrinsics_mips64.cc
@@ -1299,6 +1299,8 @@
   if (type == Primitive::kPrimLong) {
     __ Lld(out, TMP);
   } else {
+    // Note: We will need a read barrier here, when read barrier
+    // support is added to the MIPS64 back end.
     __ Ll(out, TMP);
   }
   __ Dsubu(out, out, expected);         // If we didn't get the 'expected'