Remove object_utils.h.

Break into object_lock, field_helper and method_helper.
Clean up header files following this.
Also tidy some of the Handle code in response to compiler errors when resolving
the changes in this CL.

Change-Id: I73e63015a0f02a754d0866bfaf58208aebcaa295
diff --git a/runtime/mirror/class.cc b/runtime/mirror/class.cc
index be05fb8..fadf80e 100644
--- a/runtime/mirror/class.cc
+++ b/runtime/mirror/class.cc
@@ -18,17 +18,16 @@
 
 #include "art_field-inl.h"
 #include "art_method-inl.h"
-#include "class-inl.h"
 #include "class_linker.h"
 #include "class_loader.h"
+#include "class-inl.h"
 #include "dex_cache.h"
 #include "dex_file-inl.h"
 #include "gc/accounting/card_table-inl.h"
-#include "object-inl.h"
-#include "object_array-inl.h"
-#include "object_utils.h"
-#include "runtime.h"
 #include "handle_scope-inl.h"
+#include "object_array-inl.h"
+#include "object-inl.h"
+#include "runtime.h"
 #include "thread.h"
 #include "throwable.h"
 #include "utils.h"