General code refactoring

- style cleanup
- removed NULL checks in places where they are not currently needed
- use isc_refcount for dispatch reference counting
- revised code flow for readability
- remove some #ifdefs that are no longer relevant
- remove unused struct members
- removed unnecessary function parameters
- use C99 struct initialization

lib/ns/tests/nstest.c

@@ -236,8 +236,8 @@ create_managers(void) {
 	CHECK(dns_dispatchmgr_create(mctx, &dispatchmgr));
 
 	CHECK(ns_interfacemgr_create(mctx, sctx, taskmgr, timermgr, socketmgr,
-				     netmgr, dispatchmgr, maintask, ncpus, NULL,
-				     ncpus, &interfacemgr));
+				     netmgr, dispatchmgr, maintask, NULL, ncpus,
+				     &interfacemgr));
 
 	CHECK(ns_listenlist_default(mctx, port, -1, true, &listenon));
 	ns_interfacemgr_setlistenon4(interfacemgr, listenon);