Set a proper type for a variable (#42453)
Summary:
`ninputs` variable was always used as a `size_t` but declared as an `int32_t`
Now, some annoying warnings are fixed
Pull Request resolved: https://github.com/pytorch/pytorch/pull/42453
Reviewed By: agolynski
Differential Revision: D22898282
Pulled By: mrshenli
fbshipit-source-id: b62d6b07f0bc3717482906df6010d88762ae0ccd
