[Bug libstdc++/115799] ranges::find's optimized branching for memchr is not quite right

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115799

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
It does, but can't use if-constexpr in c++98 mode.