Rename ObjPtr::Decode to ObjPtr::Ptr

Done to prevent ambiguity with ScopedObjectAccess::Decode.

Bug: 31113334

Test: test-art-host
Change-Id: I07a2497cc9cf66386311798933547471987fc316
diff --git a/patchoat/patchoat.cc b/patchoat/patchoat.cc
index b259f64..f3eb663 100644
--- a/patchoat/patchoat.cc
+++ b/patchoat/patchoat.cc
@@ -505,7 +505,7 @@
   void Visit(ArtField* field) OVERRIDE REQUIRES_SHARED(Locks::mutator_lock_) {
     ArtField* const dest = patch_oat_->RelocatedCopyOf(field);
     dest->SetDeclaringClass(
-        patch_oat_->RelocatedAddressOfPointer(field->GetDeclaringClass().Decode()));
+        patch_oat_->RelocatedAddressOfPointer(field->GetDeclaringClass().Ptr()));
   }
 
  private: