[Bug c++/60304] Including <atomic> disables -Wconversion-null

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60304

--- Comment #14 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Ah, as stdbool.h documents, using it in C++ (apparently meant C++98) is a GNU
extension, and for that I bet having those macros is desirable.
And then there is C++11 [support.runtime]/8 that requires it is not done:
"The header <cstdbool> and the header <stdbool.h> shall not define macros named
bool, true, or false."
So, perhaps those macros should be conditional on C++ version?