explicitly provide memory format when calling to clone() at TensorShape.cpp
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/28698
Test Plan: Imported from OSS
Differential Revision: D18333352
Pulled By: ifedan
fbshipit-source-id: cb31d4bbda50a6bfa7a25d0cae9953bec03e7c46
