[Bug libstdc++/110653] Support std::stoi etc. without C99 APIs

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110653

--- Comment #9 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to dave.anglin from comment #8)
> or maybe "using::strtold" additions are needed to various cstdlib files in
> gcc.

Yes, that's the problem.