Fix/Update copyright notices; Add SPDX annotation

Let's fix some erroneous/accidential references to wrong license,
update copyright information where applicable and introduce a
SPDX-License-Identifier to all files.

Change-Id: I39af26c6aaaf5c926966391f6565fc5936be21af
diff --git a/include/osmocom/core/bitcomp.h b/include/osmocom/core/bitcomp.h
index dc356bd..5faa5ea 100644
--- a/include/osmocom/core/bitcomp.h
+++ b/include/osmocom/core/bitcomp.h
@@ -1,10 +1,12 @@
 /*! \file bitcomp.h
  *  Osmocom bit compression routines. */
 /*
- * (C) 2016 sysmocom s.f.m.c. GmbH by Max Suraev <msuraev@sysmocom.de>
- *
+ * (C) 2016 by sysmocom - s.f.m.c. GmbH
+ * Author: Max Suraev <msuraev@sysmocom.de>
  * All Rights Reserved
  *
+ * SPDX-License-Identifier: GPL-2.0+
+ *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
diff --git a/include/osmocom/core/bitvec.h b/include/osmocom/core/bitvec.h
index 19466ab..c9bab39 100644
--- a/include/osmocom/core/bitvec.h
+++ b/include/osmocom/core/bitvec.h
@@ -1,6 +1,6 @@
 /* (C) 2009 by Harald Welte <laforge@gnumonks.org>
  * (C) 2012 Ivan Klyuchnikov
- * (C) 2015 Sysmocom s.f.m.c. GmbH
+ * (C) 2015 sysmocom - s.f.m.c. GmbH
  *
  * All Rights Reserved
  *
diff --git a/include/osmocom/core/stats.h b/include/osmocom/core/stats.h
index f50796c..e4d46ba 100644
--- a/include/osmocom/core/stats.h
+++ b/include/osmocom/core/stats.h
@@ -1,5 +1,5 @@
 /*
- * (C) 2015 by Sysmocom s.f.m.c. GmbH
+ * (C) 2015 by sysmocom - s.f.m.c. GmbH
  *
  * All Rights Reserved
  *