[Bug libstdc++/96803] std::tuple chooses wrong constructor for uses-allocator construction

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96803

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
This is not a regression, it's been wrong since I added uses-allocator
construction in r174443.