[libcxx-commits] [libcxx] [libc++] Partially implement P2846R6: `reserve_hint` (PR #206385)

[A. Jiang via libcxx-commits]

https://github.com/frederick-vs-ja approved this pull request.

I think this can be merged. But perhaps someone else should confirm

https://github.com/llvm/llvm-project/pull/206385