This is a follow-up of 75aec4703d. There, I updated the wrapper to only include llvm/ADT/Optional.h for LLVM version below 16. But I missed updating some of the None references. Found by our experimental rust + llvm at HEAD bot: https://buildkite.com/llvm-project/rust-llvm-integrate-prototype/builds/15587#0185006b-e0af-49e5-8b06-280ed125ff0d/200-539
75aec4703d