[llvm] [ASan] Protect against scalable vectors in FunctionStackPoisoner. (PR #155357)

[Thurston Dang via llvm-commits]

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

Thanks for the patch!

Nit: the title is ambiguous. "Protect against scalable vectors" could be misinterpreted to mean that scalar vectors will have use-after-scope protection; this patch is actually deliberately not attempting instrumentation for scalable vectors.

https://github.com/llvm/llvm-project/pull/155357