ART: More header cleanups

Clean up some more includes. Move some -inls from object-inl to
object-refvisitor-inl. Fix up transitives.

Test: m test-art-host
Change-Id: I0e3e268d95a1c71b0a80fc963d13d191a97b2283
diff --git a/runtime/mirror/class_loader.h b/runtime/mirror/class_loader.h
index 6e1f44b..381d96b 100644
--- a/runtime/mirror/class_loader.h
+++ b/runtime/mirror/class_loader.h
@@ -17,7 +17,10 @@
 #ifndef ART_RUNTIME_MIRROR_CLASS_LOADER_H_
 #define ART_RUNTIME_MIRROR_CLASS_LOADER_H_
 
+#include "base/mutex.h"
 #include "object.h"
+#include "object_reference.h"
+#include "obj_ptr.h"
 
 namespace art {