[libclc] [llvm] [libclc][CMake] Use clang/llvm-ar on Windows (PR #186726)

[Joseph Huber via cfe-commits]

jhuber6 wrote:

> I'm just trying to figure out if there is something to fix, or if I need to set up my configuration differently.

I think treating this as an external project is likely the correct thing to do, as that's how LLVM handles it internally. Either that or run two CMake jobs yourself. Fundamentally this is cross-compiling so you should think of the toolchain requirements similarly.

https://github.com/llvm/llvm-project/pull/186726