[llvm] [LLVM][Verifier] Move intrinsic signature verification to declarations (PR #204478)

[Rahul Joshi via llvm-commits]

jurahul wrote:

I am testing a new solution, using `Module::isMaterialized` to control check on declarations with no uses. That seems to address the ThinLTO case. For lazily loaded modules, it seems we keep the old (bad) signatures around since they may have references in not-yet materialized function bodies. 

https://github.com/llvm/llvm-project/pull/204478