make a way to disable callgrind (#46116)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/46116
Ideally I would just use one of the existing preprocessor flags such as `FBCODE_CAFFE2`, but this implies a whole bunch of other things elsewhere, so it is not really a solution for ovrsource.
Test Plan: CI green, we are able to disable it internally with `-DNVALGRIND`
Reviewed By: malfet
Differential Revision: D24227360
fbshipit-source-id: 24a3b393cf46d6a16acca0a9ec52610d4bb8704f
