Move most mirror:: args to ObjPtr

Fixed possible moving GC bugs in ClinitImageUpdate class.

Bug: 31113334

Test: test-art-host
Change-Id: I0bf6578553d58b944aaa17665f1350bdf5ed15ec
diff --git a/runtime/mirror/class_loader.h b/runtime/mirror/class_loader.h
index 407678a..a62a460 100644
--- a/runtime/mirror/class_loader.h
+++ b/runtime/mirror/class_loader.h
@@ -67,7 +67,7 @@
             VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags,
             ReadBarrierOption kReadBarrierOption = kWithReadBarrier,
             typename Visitor>
-  void VisitReferences(mirror::Class* klass, const Visitor& visitor)
+  void VisitReferences(ObjPtr<Class> klass, const Visitor& visitor)
       REQUIRES_SHARED(Locks::mutator_lock_)
       REQUIRES(!Locks::classlinker_classes_lock_);