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/assembler_x86.cc b/src/assembler_x86.cc
index 5df8704..c7b2bb5 100644
--- a/src/assembler_x86.cc
+++ b/src/assembler_x86.cc
@@ -1797,7 +1797,7 @@
   X86Assembler* sp_asm = down_cast<X86Assembler*>(sasm);
 #define __ sp_asm->
   __ Bind(&entry_);
-  // NB the return value is dead
+  // Note: the return value is dead
   // Pass exception as argument in EAX
   __ fs()->movl(EAX, Address::Absolute(Thread::ExceptionOffset()));
   __ fs()->call(Address::Absolute(OFFSETOF_MEMBER(Thread, pDeliverException)));