[Bug libstdc++/83328] string.insert does not return a iterator when using initializer lists

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83328

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
I guess include/debug/string should be adjusted too.