[llvm] [WebAssembly] Fix lowering of (extending) loads from addrspace(1) globals (PR #155937)

[Derek Schuff via llvm-commits]

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

I think this is in a place where it's workable now, and maybe it makes more sense to iterate on it after landing.
There's still a case to be made for trapping rather than trying to explicitly handle known-UB cases, we can think more about that.
It also made me think, what about intrinsics like memcpy? Atomics? I'm sure there are other weird cases that make no sense but might pop out.

https://github.com/llvm/llvm-project/pull/155937