[llvm] [AArch64] Initial compiler support for SVE unwind on Windows. (PR #138609)

[Benjamin Maxwell via llvm-commits]

https://github.com/MacDue approved this pull request.

LGTM, thanks for addressing my comments :+1:. I'm not entirely certain that everything is exactly right here (I don't personally work on Windows targets), but I don't think this should have any impact on SVE for non-Windows targets, so in that sense, I consider this a fairly safe change. 

Please wait a few days to see if anyone else has comments before landing.

https://github.com/llvm/llvm-project/pull/138609