[master] 30fca975e cache_ban: Flexelint banidx

[Dridi Boukelmoune]

> It's probably just that we never used NFIND before so flexelint didn't
> have a reason to complain until now.

I was very wrong, we mean to constify them!

See tools/import_vtree_from_freebsd.sh:

    /(VRBT_FIND|VRBT_NFIND|VRBT_MINMAX)/{
    s/struct name [*]/const struct name */
    s/, struct type [*]/, const struct type */
    }

I'm not sure what went wrong last time it got imported.

Dridi