cosmetic: Update copyright statement, license notice and SPDX

Some of our files didn't have a copyright notice at all, let's add
it.  Also, update the notices in other files and ensure a SPDX
identifier is present in all but the most trivial files.

Change-Id: If7fa19ce484b415bc645e39b3d0d666b44b5f0fd
diff --git a/msc/MSC_Tests.ttcn b/msc/MSC_Tests.ttcn
index 0d6083e..16f7b9b 100644
--- a/msc/MSC_Tests.ttcn
+++ b/msc/MSC_Tests.ttcn
@@ -1,5 +1,17 @@
 module MSC_Tests {
 
+/* Osmocom MSC test suite in in TTCN-3
+ * (C) 2017-2019 Harald Welte <laforge@gnumonks.org>
+ * (C) 2018-2019 sysmocom - s.f.m.c. GmbH
+ * (C) 2018-2019 Vadim Yanitskiy <axilirator@gmail.com>
+ * All rights reserved.
+ *
+ * Released under the terms of GNU General Public License, Version 2 or
+ * (at your option) any later version.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
 friend module MSC_Tests_Iu;
 
 import from General_Types all;