ART: Add object-readbarrier-inl.h

Move some read-barrier code into a new header. This prunes the
include tree for the concurrent-copying collector. Clean up other
related includes.

Test: mmma art
Change-Id: I40ce4e74f2e5d4c692529ffb4df933230b6fd73e
diff --git a/runtime/openjdkjvmti/events.cc b/runtime/openjdkjvmti/events.cc
index 521494a..0ec92b7 100644
--- a/runtime/openjdkjvmti/events.cc
+++ b/runtime/openjdkjvmti/events.cc
@@ -36,10 +36,11 @@
 #include "gc/allocation_listener.h"
 #include "gc/gc_pause_listener.h"
 #include "gc/heap.h"
+#include "handle_scope-inl.h"
 #include "instrumentation.h"
 #include "jni_env_ext-inl.h"
 #include "mirror/class.h"
-#include "mirror/object.h"
+#include "mirror/object-inl.h"
 #include "runtime.h"
 #include "ScopedLocalRef.h"
 #include "scoped_thread_state_change-inl.h"