Re: [PATCH] cocci: remove 'unused.cocci'

> When 'unused.cocci' was added in 4f40f6cb73 (cocci: add and apply a
> rule to find "unused" strbufs, 2022-07-05) it found three unused
> strbufs, and when it was generalized in the next commit it managed to
> find an unused string_list as well.  That's four unused variables in
> over 17 years, so apparently we rarely make this mistake.
>
> Unfortunately, applying 'unused.cocci' is quite expensive, e.g. it
> increases the from-scratch runtime of 'make coccicheck' by over 5:30
> minutes or over 160%:
> ...
> That's a lot of runtime spent for not much in return, and arguably an
> unused struct instance sneaking in is not that big of a deal to
> justify the significantly increased runtime.
>
> Remove 'unused.cocci', because we are not getting our CPU cycles'
> worth.