[clang] [CIR] Implement cir.cmp3way Operation (PR #186294)

[Erich Keane via cfe-commits]

https://github.com/erichkeane commented:

See: https://github.com/llvm/llvm-project/pull/169963/changes

This might have been now implemented by 2 people.  @andykaylor @HendrikHuebner 

https://github.com/llvm/llvm-project/pull/186294