[llvm] [IRMover] Don't consider opaque types isomorphic to other types (PR #138241)

[Nikita Popov via llvm-commits]

nikic wrote:

> Few questions below so that I understand it better. Also, what is the real world impact of removing this support for LTO'ed binaries? Regardless of whether it is technically correct, looks like it has existed for a long time.

I'd expect the impact to be close to zero. After the opaque pointers migration, it's pretty hard to run into an opaque type at all.

https://github.com/llvm/llvm-project/pull/138241