[llvm] [Exegesis] CPU selection, when native arch and target mismatch (PR #131014)

[via llvm-commits]

AnastasiyaChernikova wrote:

As an alternative - I can suggest not to install native by default. When checking for cross-compilation, give an error if the user manually installed native, in other cases choose generic. And not for cross-compilation, install native after that, without actually changing the logic. 
@boomanaiden154  Would that be better?

https://github.com/llvm/llvm-project/pull/131014