[Bug libstdc++/114863] std::format applying grouping to nan's and inf's

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114863

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Maybe we could also make _M_localize more efficient for finite values by not
even attempting to use grouping for scientific format.