[Bug libstdc++/115885] Build errors when libstdc++ math.h included in extern "C" block

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115885

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Kacper Słomiński from comment #0)
> This causes the following build errors if <math.h> is included somewhere
> inside an `extern "C"` block:

Stop doing that then.