[llvm] SafeStack: Respect alloca addrspace (PR #112536)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> Maybe just fatal error if address space of PointerType::getUnqual != DL.getAllocaPtrType?

That would defeat the point. It does produce an error if the realized __safestack_unsafe_stack_ptr type is wrong, test added



https://github.com/llvm/llvm-project/pull/112536