Add native support for FinalizerList.makeCircularListIfUnenqueued

Called from FinalizerReference.enqueueSentinelReference to prevent
a race where the GC updates pendingNext of the sentinel reference
before enqueueSentinelReference.

Bug: 17462553

(cherry picked from commit 3256166df40981f1f1997a5f00303712277c963f)

Change-Id: I7ad2fd250c2715d1aeb919bd548ef9aab24f30a2
diff --git a/runtime/Android.mk b/runtime/Android.mk
index 5065c58..61bc9ff 100644
--- a/runtime/Android.mk
+++ b/runtime/Android.mk
@@ -120,6 +120,7 @@
   native/java_lang_Thread.cc \
   native/java_lang_Throwable.cc \
   native/java_lang_VMClassLoader.cc \
+  native/java_lang_ref_FinalizerReference.cc \
   native/java_lang_ref_Reference.cc \
   native/java_lang_reflect_Array.cc \
   native/java_lang_reflect_Constructor.cc \