use exe/exepath in our genrules
Pull Request resolved: https://github.com/pytorch/pytorch/pull/79626
Buck does not properly handle caching when the executable is
identified with `$(location ...)`. See
https://fb.workplace.com/groups/askbuck/posts/8600146743367198 for
more information.
Differential Revision: [D37179273](https://our.internmc.facebook.com/intern/diff/D37179273/)
**NOTE FOR REVIEWERS**: This PR has internal Facebook specific changes or comments, please review them on [Phabricator](https://our.internmc.facebook.com/intern/diff/D37179273/)!
Approved by: https://github.com/malfet
Author
Michael Andreas Dagitses
