Add Class::IsFinalizable and Object::AddFinalizerReference.

Also correctly set the special bit in Class' flags.

We need compiler support before I can go further.

Change-Id: Ib7a637d7140a6f8c416635738d4d0b57c17ad628
diff --git a/src/jni_compiler.cc b/src/jni_compiler.cc
index c8cfc66..83be88a 100644
--- a/src/jni_compiler.cc
+++ b/src/jni_compiler.cc
@@ -219,7 +219,7 @@
   //    to the convention required for a native call (shuffling). For references
   //    place an index/pointer to the reference after checking whether it is
   //    NULL (which must be encoded as NULL).
-  //    NB. we do this prior to materializing the JNIEnv* and static's jclass to
+  //    Note: we do this prior to materializing the JNIEnv* and static's jclass to
   //    give as many free registers for the shuffle as possible
   mr_conv->ResetIterator(FrameOffset(frame_size+out_arg_size));
   uint32_t args_count = 0;