[Bug c++/60512] would be useful if gcc implemented __has_feature similarly to clang

[iains at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60512

--- Comment #20 from Iain Sandoe <iains at gcc dot gnu.org> ---
although, I guess, we could have one table and somehow include the target in
predicates if appropriate...