[Bug libstdc++/107135] array<T>::at() method should not be in <array> for freestanding C++

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107135

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
We should make it terminate though, there's no definition of
__throw_out_of_range_fmt.