add SPDX identifier for files under the GPL-3+ license

Scripts/developer_scripts/test_license_check/min_dihedral_angle.h

@@ -12,9 +12,9 @@
 // This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 // WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 //
-// $URL: svn+ssh://scm.gforge.inria.fr/svn/cgal/branches/releases/CGAL-4.1-branch/Mesh_3/include/CGAL/Mesh_3/min_dihedral_angle.h $
-// $Id: min_dihedral_angle.h 67117 2012-01-13 18:14:48Z lrineau $
-// 
+// $URL$
+// $Id$
+// SPDX-License-Identifier: GPL-3.0+
 //
 // Author(s)     : Laurent RINEAU, Stephane Tayeb
 

Scripts/developer_scripts/test_license_check/test-gpl.h

@@ -9,6 +9,8 @@
 // Licensees holding a valid commercial license may use this file in
 // accordance with the commercial license agreement provided with the software.
 //
+// SPDX-License-Identifier: GPL-3.0+
+//
 // This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 // WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 //