pytorch

e21c0ac9 - use exe/exepath in our genrules

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