[Bug libstdc++/65122] std::vector doesn't honor element alignment

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65122

--- Comment #21 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Created attachment 39686
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=39686&action=edit
Make new_allocator support types with new-extended alignment

This works, but currently produces a warning due to PR 77742.