Avoid dtype mismatch error in `torch.save` if storages are unallocated (#68787)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/58970
cc mruberry
Pull Request resolved: https://github.com/pytorch/pytorch/pull/68787
Reviewed By: mruberry
Differential Revision: D32617425
Pulled By: anjali411
fbshipit-source-id: fe7f2374e4ef4428346a0a202cae8e0d382e03ab
