[Bug libstdc++/123167] to_chars(long double) produces rubbish with -mlong-double-64

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123167

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Right, there is no expectation that the libstdc++.so symbols work for every
possible combination of compiler options.