[c10] remove warning attribute does not apply to any entity (#34018)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/34018
Remove warning
```
caffe2/c10/util/ArrayRef.h(278): warning: attribute does not apply to any entity
```
Test Plan: CI
Reviewed By: jianyuh
Differential Revision: D20181191
fbshipit-source-id: 58bd168a87a94fec925c7cde8b8d728a4257446c
