[libcxx-commits] [libcxx] Replace ::new with construct_at in allocator. (PR #105593)

[A. Jiang via libcxx-commits]

frederick-vs-ja wrote:

Not sure whether change should be made here. Note that 

IIUC LWG3315 can only be considered as a patch for [P0784R7](https://wg21.link/p0784r7)/C++20, not to earlier standard revisions, and the operations in "Default" are specified for `allocator_traits`, which has been implemented in LLVM 12.0. Also, the `construct` and `destroy` member functions of `std::allocator` are removed in C++20.

https://github.com/llvm/llvm-project/pull/105593