dns/ldns: Fix ldns-config
After the last update ldns-config is producing wrong information and at least
dns/opendnssec and dns/opendnssec2 are failing to build.
PR: 240297
Submitted by: Jaap Akkerhuis <jaap@NLnetLabs.nl> (maintainer)
Reported by: Roman Serbski <mefystofel@gmail.com>