[Bug libstdc++/78486] feature request: std::iu16stringstream std::ou16stringstream, and utf8

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78486

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Do these exist in standard C++ at all?  If not then I doubt they will be added
to the GCC's library.