P0591R4 Utility Functions For Uses-Allocator Construction
LWG-3185 Uses-allocator construction functions missing constexpr and noexcept
LWG-3187 P0591R4 reverted LWG-2586 fixes to scoped_allocator_adaptor::construct()
LWG-3321 uninitialized_construct_using_allocator should use construct_at
This should be implemented together with #19, P0475R1 Guaranteed Copy Elision For Piecewise Construction.