[Bug c/80685] -Wnonnull-compare warns based on builtin declaration

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80685

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Use -fno-builtins if you don't want gcc to assumes things about functions.