[Bug libstdc++/124714] std module (std.cc) should check for __float128 support

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124714

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
acoshl has nothing to do with float128.
It is about long double which in theory could be the same size as double.