More threads work.

Adds stubs (and sometimes implementations) for dalvik.system.VMStack and
java.lang.Thread native methods. There was a bug in the dalvik
thread priority setting code, where the current thread and the passed-in
thread were confused.

I've also pulled Mutex and ThreadList out into their own files, and
moved some functionality around (with the aim of having more stuff
private, especially locks).

Change-Id: Ieb0f22669cac3df44ca34f7868f8e7d4dfa09ab6
diff --git a/src/runtime.h b/src/runtime.h
index 99caa29..bcb118c 100644
--- a/src/runtime.h
+++ b/src/runtime.h
@@ -92,7 +92,7 @@
   // Detaches the current native thread from the runtime.
   void DetachCurrentThread();
 
-  void DumpStatistics(std::ostream& os);
+  void Dump(std::ostream& os);
 
   ~Runtime();