Fix torch.nonzero type annotation (#51635)
Summary:
The overloads are a little tricky here. It's important that the overloads are such that it's unambiguous what
`torch.nonzero(x)` will resolve to - so just specify defaults for one of the overloads. Also, `out` is left out of the second overload
because a non-None value for `out` is not valid in combination with `as_tuple=True`.
Closes gh-51434
Pull Request resolved: https://github.com/pytorch/pytorch/pull/51635
Reviewed By: zhangguanheng66
Differential Revision: D26279203
Pulled By: walterddr
fbshipit-source-id: 8459c04fc9fbf7fc5f31b3f631aaac2f98b17ea6
