[clang] [z/OS] Set the default arch for z/OS to be arch10 (PR #89854)

[Fangrui Song via cfe-commits]

MaskRay wrote:

Clang configuration files https://clang.llvm.org/docs/UsersManual.html#configuration-files cover your use case and the feature is exactly designed to avoid such cmake default configs. https://blogs.gentoo.org/mgorny/2022/10/07/clang-in-gentoo-now-sets-default-runtimes-via-config-file/

You can add `-march=...` in` clang.cfg` beside the `clang` executable.

https://github.com/llvm/llvm-project/pull/89854