unbound: Explicitly cast from ldns RR type/class to our types

These definitions are directly derived from the RFC, so it should be safe
to cast them. clang complains about the different types, so cast them
explicitly.

src/libstrongswan/plugins/unbound/unbound_rr.c

@@ -135,8 +135,8 @@ unbound_rr_t *unbound_rr_create_frm_ldns_rr(ldns_rr *rr)
 		return NULL;
 	}
 
-	this->type = ldns_rr_get_type(rr);
-	this->class = ldns_rr_get_class(rr);
+	this->type = (rr_type_t)ldns_rr_get_type(rr);
+	this->class = (rr_class_t)ldns_rr_get_class(rr);
 	this->ttl = ldns_rr_ttl(rr);
 	for(i = 0; i < ldns_rr_rd_count(rr); i++)
 	{