[clang] [Driver] Normalize the baremetal handling of libc++ and runtimes (PR #101259)

[Louis Dionne via cfe-commits]

ldionne wrote:

> > Gentle ping @petrhosek
> 
> I'd like to go ahead and merge this PR but I still need someone to approve this change.

Sorry, somehow I thought this was waiting on a reply from you.

https://github.com/llvm/llvm-project/pull/101259