[clang] [llvm] [Clang][Driver] Add an option to control loop-interchange (PR #125830)

[Sjoerd Meijer via cfe-commits]

sjoerdmeijer wrote:

> The other optimzation pass options (unrolll, vectorize, ...) are implemented in `PipelineTuningOptions` and `CodeGenOptions.def`. Do it the same way?

Thanks for the review and suggestion @Meinersbur, that's now implemented in the latest revision. 

https://github.com/llvm/llvm-project/pull/125830