libstdc++: Add missing std::tuple constructor [PR114147]
I caused a regression with commit r10-908 by adding a constraint to the
non-explicit allocator-extended default constructor, but seemingly
forgot to add an explicit overload with the corresponding constraint.
libstdc++-v3/ChangeLog:
PR libstdc++/114147
* include/std/tuple (tuple::tuple(allocator_arg_t, const Alloc&)):
Add missing overload of allocator-extended default constructor.
(tuple<T1,T2>::tuple(allocator_arg_t, const Alloc&)): Likewise.
* testsuite/20_util/tuple/cons/114147.cc: New test.
(cherry picked from commit
0a545ac7000501844670add0b3560ebdbcb123c6)