Style cleanup for ObjPtr<>-ify changes.

Replace "ObjPtr<.> const" with "const ObjPtr<.>".

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Bug: 31113334
Change-Id: I5a1c080bc88b091e15ee9eb0bb1ef6f6f290701c
diff --git a/runtime/mirror/object.cc b/runtime/mirror/object.cc
index f6adc80..b8d1d3f 100644
--- a/runtime/mirror/object.cc
+++ b/runtime/mirror/object.cc
@@ -71,7 +71,7 @@
   void VisitRoot(mirror::CompressedReference<mirror::Object>* root ATTRIBUTE_UNUSED) const {}
 
  private:
-  ObjPtr<Object> const dest_obj_;
+  const ObjPtr<Object> dest_obj_;
 };
 
 Object* Object::CopyObject(ObjPtr<mirror::Object> dest,