fix make clean for ldns examples
fix make clean for ldns examples

threatstack/libldns,NLnetLabs/ldns,threatstack/libldns,threatstack/libldns,threatstack/libldns,NLnetLabs/ldns,gegenschall/ldns,gegenschall/ldns,NLnetLabs/ldns,gegenschall/ldns,benlaurie/ldns,benlaurie/ldns,gegenschall/ldns,NLnetLabs/ldns,threatstack/libldns,benlaurie/ldns,benlaurie/ldns