[llvm] [GlobalISel] use constexpr LLT types when creating ISel data (PR #191574)

[Demetrius Kanios via llvm-commits]

QuantumSegfault wrote:

Thank you! I believe this solves #190873 that I was running into.

In regards to preference, I don't really have one. I just want it to work. I'm building GlobalISel for Wasm here upstream, and intend to migrate to `-extended-llt` ASAP (I would have already if not for this issue). Not much to "migrate" yet, so I wouldn't mind removal of the implicit `LLT::integer` == `LLT::scalar` behavior.

But as with most things, I'm sure this compat was done for a highly debated reason, so undoing it so soon seems silly.

https://github.com/llvm/llvm-project/pull/191574