[llvm] update `llvm.spec` (PR #65452)

[Tom Stellard via llvm-commits]

https://github.com/tstellar requested changes to this pull request.

I agree with @sylvestre, I think it would be best to remove it.  If you want a modern spec file for building RPMs, you can look at the [Fedora Linux spec](https://src.fedoraproject.org/rpms/llvm/blob/rawhide/f/llvm.spec)

https://github.com/llvm/llvm-project/pull/65452