[clang] [clang] Support --sysroot= for ${arch}-windows-msvc targets (PR #96417)

[Martin Storsjö via cfe-commits]

mstorsjo wrote:

> Btw relying on wine is another thing i think is no-go.

Just to be clear - nobody here has suggested using wine for anything here. My repo http://github.com/mstorsjo/msvc-wine/ contains pure python/shell/perl scripts for downloading and unpacking MSVC. No wine needed. It also contains shell script wrappers for transparently using MSVC as if it was a native tool, using wine - but that's optional, you can use it just for downloading and getting MSVC libraries for use with Clang/LLVM without any use of wine anywhere. The repo name predates the downloader/unpacker.

https://github.com/llvm/llvm-project/pull/96417