move generated-autograd-headers to the shared build structure
Pull Request resolved: https://github.com/pytorch/pytorch/pull/76183
This is a relatively simple target but we have to fix our header
expansion to understand generated files. Next step will be to use this
in Bazel.
Differential Revision: [D35820541](https://our.internmc.facebook.com/intern/diff/D35820541/)
**NOTE FOR REVIEWERS**: This PR has internal Facebook specific changes or comments, please review them on [Phabricator](https://our.internmc.facebook.com/intern/diff/D35820541/)!
Approved by: https://github.com/dreiss, https://github.com/malfet
Author
Michael Andreas Dagitses
