[llvm] InferAddressSpaces: Handle llvm.fake.use (PR #109567)

[Stephen Tozer via llvm-commits]

https://github.com/SLTozer commented:

Although `llvm.fake.use` is variadic, it's actually an error to have more than one argument (not enforced in the verifier, I'll add a patch for that) - the variadic type is only used to allow it to be generic, since the expectation is that it can take any type (and we don't want a unique declaration for every type that may be used). The tests can be updated to remove the `multiple_` cases, and the code can assume that there is only one operand. Aside from that, this LGTM, acknowledging that I have limited understanding of InferAddressSpaces (but gave the relevant functions a read to make sure the updates make sense).

https://github.com/llvm/llvm-project/pull/109567