[NFC] Remove non-rvlaue non-variadic allocator::construct overloads.

[zoecarver]

Summary

All supported compilers have rvalues and variadics so we can safely remove the overloads of allocator::construct which are only enabled on compilers without rvalues and variadics.

[ldionne]

Here too, please run with C++03 and ship it if it passes (it should).

libcxx/include/memory

#endif
 
     _LIBCPP_INLINE_VISIBILITY void deallocate(_Tp* __p, size_t __n) _NOEXCEPT
         {_VSTD::__libcpp_deallocate((void*)__p, __n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp));}
 
 #if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS)
     _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_INLINE_VISIBILITY size_type max_size() const _NOEXCEPT
         {return size_type(~0) / sizeof(_Tp);}
 
-#if !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES) && !defined(_LIBCPP_HAS_NO_VARIADICS)
     template <class _Up, class... _Args>
         _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_INLINE_VISIBILITY
         void
         construct(_Up* __p, _Args&&... __args)
         {
             ::new((void*)__p) _Up(_VSTD::forward<_Args>(__args)...);
         }
-#else  // !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES) && !defined(_LIBCPP_HAS_NO_VARIADICS)
-        _LIBCPP_INLINE_VISIBILITY
-        void
-        construct(pointer __p)
-        {
-            ::new((void*)__p) _Tp();
-        }
-# if defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES)
-
-    template <class _A0>
-        _LIBCPP_INLINE_VISIBILITY
-        void
-        construct(pointer __p, _A0& __a0)
-        {
-            ::new((void*)__p) _Tp(__a0);
-        }
-    template <class _A0>
-        _LIBCPP_INLINE_VISIBILITY
-        void
-        construct(pointer __p, const _A0& __a0)
-        {
-            ::new((void*)__p) _Tp(__a0);
-        }
-# endif  // defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES)
-    template <class _A0, class _A1>
-        _LIBCPP_INLINE_VISIBILITY
-        void
-        construct(pointer __p, _A0& __a0, _A1& __a1)
-        {
-            ::new((void*)__p) _Tp(__a0, __a1);
-        }
-    template <class _A0, class _A1>
-        _LIBCPP_INLINE_VISIBILITY
-        void
-        construct(pointer __p, const _A0& __a0, _A1& __a1)
-        {
-            ::new((void*)__p) _Tp(__a0, __a1);
-        }
-    template <class _A0, class _A1>
-        _LIBCPP_INLINE_VISIBILITY
-        void
-        construct(pointer __p, _A0& __a0, const _A1& __a1)
-        {
-            ::new((void*)__p) _Tp(__a0, __a1);
-        }
-    template <class _A0, class _A1>
-        _LIBCPP_INLINE_VISIBILITY
-        void
-        construct(pointer __p, const _A0& __a0, const _A1& __a1)
-        {
-            ::new((void*)__p) _Tp(__a0, __a1);
-        }
-#endif  // !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES) && !defined(_LIBCPP_HAS_NO_VARIADICS)
     _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_INLINE_VISIBILITY void destroy(pointer __p) {__p->~_Tp();}
 #endif
 };
 
 template <class _Tp>
 class _LIBCPP_TEMPLATE_VIS allocator<const _Tp>
 {
 public: