Add "PrivServer" test which exercises DBusServer and dbus_shutdown

Add "PrivServer" test which exercises DBusServer and dbus_shutdown

	* test/data/valid-service-files/org.freedesktop.DBus.TestSuite.PrivServer.service.in:
	New service file for PrivServer.
	* configure.in: Generate it.
	* test/name-test/Makefile.am: Build test-privserver and
	test-privserver-client.
	* test/name-test/test-privserver.c: Use DBusServer to
	serve a private connection.
	* test/name-test/test-privserver-client.c: Connect
	via session bus and get address of private server,
	exercise dbus_shutdown().
	* test/name-test/run-test.sh: Run it.