Stop daemon threads in runtime shutdown

Ensure that daemons are stopped and joins before bringing down the
runtime. This fixes bugs related to native code still running when
we shutdown the runtime.

Also changed the mutex destructor to allow contenders if we are
deleting a monitor lock level mutex.

Bug: 18577101
Change-Id: I6457b35fd69c6997b9003b5f15f39861749843a9
diff --git a/runtime/well_known_classes.h b/runtime/well_known_classes.h
index d651b90..cb75e6e 100644
--- a/runtime/well_known_classes.h
+++ b/runtime/well_known_classes.h
@@ -80,6 +80,7 @@
   static jmethodID java_lang_Daemons_requestGC;
   static jmethodID java_lang_Daemons_requestHeapTrim;
   static jmethodID java_lang_Daemons_start;
+  static jmethodID java_lang_Daemons_stop;
   static jmethodID java_lang_Double_valueOf;
   static jmethodID java_lang_Float_valueOf;
   static jmethodID java_lang_Integer_valueOf;