[llvm-branch-commits] [PowerPC][AIX] Mark LowerCommentStringPass as RequiredPassInfoMixin (PR #212018)

[Aiden Grossman via llvm-branch-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/212018

Directly using isRequired is deprecated and PassInfoMixin will soon be
moved to a detail namespace.