- Fix compile warning when threads disabled.

doc/Changelog

@@ -3,6 +3,7 @@
 	- Fix contrib/fastrpz.patch to apply cleanly.  Fix for serve-stale
 	  fixes, but it does not compile, conflicts with new rpz code.
 	- Fix to clean memory leak of respip_addr.lock when ip_tree deleted.
+	- Fix compile warning when threads disabled.
 
 10 February 2020: George
 	- Document 'ub_result.was_ratelimited' in libunbound.

respip/respip.c

@@ -75,6 +75,9 @@ resp_addr_del(rbnode_type* n, void* ATTR_UNUSED(arg))
 {
 	struct resp_addr* r = (struct resp_addr*)n->key;
 	lock_rw_destroy(&r->lock);
+#ifdef THREADS_DISABLED
+	(void)r;
+#endif
 }
 
 void