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

[Romaric Jodin via cfe-commits]

rjodinchr wrote:

Yes, ninja + this PR fixes the issue. Previously I was testing without that PR, that's why I had to patch llvm.

I will move away from Visual Studio then, thank you for the help 🙏

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