[llvm] [libc][ci] Add libc-shared-test CI for MSVC and QEMU for several archs. (PR #188553)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 commented:

Looks like CI load is not going to be an issue with all of these jobs finishing in <5 minutes.

https://github.com/llvm/llvm-project/pull/188553