[Bug c++/79433] __has_include reports wrong result for std headers that #error on __cplusplus

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79433

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
__has_include just says the include exists and not if the include file works.