[master] expanded libns unit tests

4772.	[test]		Expanded unit testing framework for libns, using
			hooks to interrupt query flow and inspect state
			at specified locations. [RT #46173]

lib/ns/tests/testdata/query/foo.db

@@ -0,0 +1,15 @@
+; Copyright (C) 2017  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/.
+
+$TTL 3600
+@		IN	SOA	localhost. postmaster.localhost. (
+				1		;serial
+				3600		;refresh
+				1800		;retry
+				604800		;expiration
+				3600 )		;minimum
+		IN	NS	ns
+ns		IN	A	127.0.0.1