[Bug libstdc++/100824] ranges::size should treat the subexpression as an lvalue

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100824

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I didn't completely implement p2091r0 which changed the value categories that
these CPOs are expression-equivalent to.