move GENERATED_CPP_CUDA to caffe2/build.bzl
Pull Request resolved: https://github.com/pytorch/pytorch/pull/77744
This is needed by gen_aten and it's immediate downstream libraries. As
such, it can live solely in the shared build structure.
Differential Revision: [D36480812](https://our.internmc.facebook.com/intern/diff/D36480812/)
**NOTE FOR REVIEWERS**: This PR has internal Facebook specific changes or comments, please review them on [Phabricator](https://our.internmc.facebook.com/intern/diff/D36480812/)!
Approved by: https://github.com/kit1980
Author
Michael Andreas Dagitses
