Fix compute_non_overlapping_and_dense() (#28551)
Summary:
There are some cases when compute_non_overlapping_and_dense() doesn't work properly:
Example:
```
Tensor t = at::tensor(1).expand({1, 3, 2});
EXPECT_FALSE(t.is_contiguous());
EXPECT_FALSE(t.is_non_overlapping_and_dense()); //FAIL!!!
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/28551
Differential Revision: D18115570
Pulled By: ifedan
fbshipit-source-id: 35b1a9473a28037d41f7177a8de23ffefa7faa13
