[llvm] [ASan][Windows] Fixing Windows shadow memory address for arm64 (PR #184902)

[Zack Johnson via llvm-commits]

zacklj89 wrote:

> The change LGTM. Even if the PR gates don't actually test windows on arm64, other forks may run them and those would be benefit (and become monitors of the continued correctness of) at least a trivial test case here.
> 
> Do you have a minimal `lit` test we could add to validate this? I think normally for changes in the codegen pass we wouldn't use lit, but this change seems so small that `lit` may be a better fit.

@davidmrdavid I added an instrumentation test that is basically just [dynamic-shadow-darwin.ll](https://github.com/llvm/llvm-project/blob/main/llvm/test/Instrumentation/AddressSanitizer/dynamic-shadow-darwin.ll) for Windows

https://github.com/llvm/llvm-project/pull/184902