[Bug libstdc++/89825] Jump table for variant visitation could be shortened for never empty variants

[antoshkka at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89825

--- Comment #1 from Antony Polukhin <antoshkka at gmail dot com> ---
There's a typo in proposed solution: it should be `&& !_Never_empty` in
`_Multi_array`.