[clang] [Driver] Add ExclusiveGroup feature to multilib.yaml. (PR #69447)

[Fangrui Song via cfe-commits]

MaskRay wrote:

> (btw, that `squash!` commit contains the revised commit message I plan to put on the final version, so I need to not forget to do the squash by hand to get that right)

You may edit the first comment in this PR now, and it will be propagated to the textbox when you click "Squash and merge" :)

https://discourse.llvm.org/t/force-push-and-rebase/73766 I believe the primary value appending new commits instead of rebasing is to demonstrate that the PR has been updated in the "Commits" tab. An amend without rebasing is equally good, just requiring `compare` links inserted by GitHub.

https://github.com/llvm/llvm-project/pull/69447