[Bug libstdc++/99752] ranges::find_end should return empty subrange when search range is empty

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99752

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Your example is an infinite loop because you're asking for the last occurrence
of e in an infinite range. There is no end of an infinite range.