rewrite logfileconfig system test

the logfileconfig system test did not conform to the style of
other tests, and was difficult to read and maintain. it has
been cleaned up and simplifeid in several ways:

- named.args used when appropriate so that named can be started with
  specified command line arguments, instead of having it launched
  directly from tests.sh
- unused root zone removed from named configuration
- an existing directory used instead of using 'mkdir' to create one
- dnssec-validation disabled to stop the server sending unnecessary queries

incidental fix: removed leftover debugging printfs from logconf.c.

bin/tests/system/logfileconfig/ns1/named.plainconf.in

@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+options {
+	query-source address 10.53.0.1;
+	notify-source 10.53.0.1;
+	transfer-source 10.53.0.1;
+	port @PORT@;
+	pid-file "named.pid";
+	listen-on { 10.53.0.1; };
+	listen-on-v6 { none; };
+	dnssec-validation no;
+	recursion no;
+	notify yes;
+};
+
+controls {
+	inet 10.53.0.1 port @CONTROLPORT@ allow { any; } keys { "rndc-key"; };
+};
+
+key rndc-key {
+	secret "1234abcd8765";
+	algorithm hmac-sha256;
+};