[compiler-rt] [compiler-rt][windows] Test fixups for MSVC. (PR #109887)

[Charlie Barto via llvm-commits]

barcharcraz wrote:

> LGTM with comments
> 
> set of PRs could be nicer

By "set of PRs" do you mean splitting this into multiple PRs or posting the follow-ups immediately?

https://github.com/llvm/llvm-project/pull/109887