Replace hand-rolled for(;;) traversal of ctl_conns TAILQ with

TAILQ_FOREACH().
No intentional functional change.
ok reyk@

src/usr.sbin/ntpd/control.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: control.c,v 1.11 2016/09/14 13:20:16 rzalamena Exp $ */
+/*	$OpenBSD: control.c,v 1.12 2017/01/09 14:04:31 krw Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -142,9 +142,10 @@ control_connbyfd(int fd)
 {
 	struct ctl_conn	*c;
 
-	for (c = TAILQ_FIRST(&ctl_conns); c != NULL && c->ibuf.fd != fd;
-	    c = TAILQ_NEXT(c, entry))
-		;	/* nothing */
+	TAILQ_FOREACH(c, &ctl_conns, entry) {
+		if (c->ibuf.fd == fd)
+			break;
+	}
 
 	return (c);
 }