Fix an outstanding compaction bug in interpreter.

Fixed a bug in DoFieldPut where the FieldHelper GetType could cause
thread suspension which would result in a stale obj.

Added more handles in the class linker to facilitate moving fiels
and methods in the future.

Removed un-necessarly passing handle references since these are value
types and don't need to be passed by reference.

Added a special NullHandle type which allows null handles without a
handle scope.

Change-Id: I1b51723920a2e4f4f8b2907066f578a3e879fd5b
diff --git a/runtime/jni_internal.cc b/runtime/jni_internal.cc
index 6f3317d..b51e1d5 100644
--- a/runtime/jni_internal.cc
+++ b/runtime/jni_internal.cc
@@ -3138,7 +3138,7 @@
 }
 
 bool JavaVMExt::LoadNativeLibrary(const std::string& path,
-                                  const Handle<mirror::ClassLoader>& class_loader,
+                                  Handle<mirror::ClassLoader> class_loader,
                                   std::string* detail) {
   detail->clear();