[llvm] reland [InlineAsm] wrap ConstraintCode in enum class NFC (PR #66264)

[Nick Desaulniers via llvm-commits]

nickdesaulniers wrote:

> Looks good, I spot checked the Mips and SystemZ issues I saw locally. I think some stuff just got lost in your rebase attempt. I see the buildkite checks on Linux passed on this PR and the previous one.

Thanks, looks like 142c89c381bccba1c688a90d7e9df91eaf78d4e3 is the culprit of that unittest failure on windows.

https://github.com/llvm/llvm-project/pull/66264