[Bug libstdc++/103911] std::from_chars shouldn't call isdigit

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103911

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Thanks for the report, this is now fixed on trunk. I'll backport it too.