RFR: Aarch64 cmpxchg_oop() fix

[Roman Kennke]

Aleksey spotted a bug that we apparently introduced with LRB. Let's
revert this little part:

diff -r c5a159a6b36d
src/hotspot/cpu/aarch64/gc/shenandoah/shenandoahBarrierSetAssembler_aarch64.cpp
---
a/src/hotspot/cpu/aarch64/gc/shenandoah/shenandoahBarrierSetAssembler_aarch64.cpp
Mon Apr 01 13:33:58 2019 +0200
+++
b/src/hotspot/cpu/aarch64/gc/shenandoah/shenandoahBarrierSetAssembler_aarch64.cpp
Tue Apr 02 23:09:55 2019 +0200
@@ -414,7 +414,9 @@
   }
   __ bind(done);

-  if (!is_cae) {
+  if (is_cae) {
+    __ mov(result, tmp1);
+  } else {
     __ cset(result, Assembler::EQ);
   }
 }

Testing: hotspot_gc_shenandoah on aarch64

Ok?