[Bug libstdc++/28103] std::operator<<(ostream&, string) sets badbit instead of failbit on failure

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=28103

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
For output, the requirement to set failbit was present since C++98, not added
by a DR.