Add heap poisoning support to the entrypoints.

In preparation for full compiler/managed-code support.

Enable stub_test with heap poisoning.

Bug: 12687968
Change-Id: I79fc54ce6386c0a1eb9621759bb4cc23bc393a75
diff --git a/runtime/globals.h b/runtime/globals.h
index fe699c6..d70f3ab 100644
--- a/runtime/globals.h
+++ b/runtime/globals.h
@@ -97,7 +97,7 @@
     kUseTableLookupReadBarrier;
 
 // If true, references within the heap are poisoned (negated).
-#ifdef ART_HEAP_POISONING
+#ifdef USE_HEAP_POISONING
 static constexpr bool kPoisonHeapReferences = true;
 #else
 static constexpr bool kPoisonHeapReferences = false;