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/class_linker.cc b/runtime/class_linker.cc
index 2e51cf8..267a1a2 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -42,8 +42,10 @@
 #include "intern_table.h"
 #include "interpreter/interpreter.h"
 #include "leb128.h"
+#include "method_helper.h"
 #include "oat.h"
 #include "oat_file.h"
+#include "object_lock.h"
 #include "mirror/art_field-inl.h"
 #include "mirror/art_method-inl.h"
 #include "mirror/class.h"
@@ -57,7 +59,6 @@
 #include "mirror/reference-inl.h"
 #include "mirror/stack_trace_element.h"
 #include "mirror/string-inl.h"
-#include "object_utils.h"
 #include "os.h"
 #include "runtime.h"
 #include "entrypoints/entrypoint_utils.h"