Make CheckJNI and JNI workarounds mutually exclusive...

...in the opposite direction; needing workarounds turns off CheckJNI.
This isn't necessarily a good idea, but I like the cleanup parts of
this change.

Change-Id: I708235ea3e5cc35ef90b01dd810e097e3ff9dd26
diff --git a/src/runtime_support.cc b/src/runtime_support.cc
index 2ecb02e..1828985 100644
--- a/src/runtime_support.cc
+++ b/src/runtime_support.cc
@@ -539,7 +539,7 @@
   intptr_t value = *arg_ptr;
   Object** value_as_jni_rep = reinterpret_cast<Object**>(value);
   Object* value_as_work_around_rep = value_as_jni_rep != NULL ? *value_as_jni_rep : NULL;
-  CHECK(Runtime::Current()->GetHeap()->IsHeapAddress(value_as_work_around_rep));
+  CHECK(Runtime::Current()->GetHeap()->IsHeapAddress(value_as_work_around_rep)) << value_as_work_around_rep;
   *arg_ptr = reinterpret_cast<intptr_t>(value_as_work_around_rep);
 }