databases/kyotocabinet: fix missing prototype warnings
No upstream response in 14 days, let's get this locally, because
else we get all sort of warnings in downstream ports using kc.
PR: 296665
Approved by: sunpoet (maintainer timeout)
MFH: 2026Q3
(cherry picked from commit 76a04c511595baf51d75ec318be553ef827205ef)