[Bug libstdc++/71579] type_traits miss checks for type completeness in some traits

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71579

--- Comment #10 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Yes I noticed is_nothrow_invocable_r was missing but forgot to mention it.