[llvm] [TableGen] Fix non-deterministic output from emitGetRegClassFromMatchKindFunc. (PR #218560)

[Sam Elliott via llvm-commits]

https://github.com/lenary commented:

I've gone back and forth on this.

I think it works, but I also took a look through the history and the programmers guide and saw that people are using MapVector or SortedVectorMap instead. I'm not sure how to decide between these choices.

https://github.com/llvm/llvm-project/pull/218560