[libcxx-commits] [libcxx] [libc++] Make `std::__tree_node` member private to prepare for UB removal (PR #154225)

[Nikolas Klauser via libcxx-commits]

https://github.com/philnik777 approved this pull request.

The AIX bots look unrelated (it's also failing in other PRs), so I don't think that's blocking.

https://github.com/llvm/llvm-project/pull/154225