Adds a license file used in mthread plugin.

headers/close-source/JCF_LGPL

+
+Copyright (C) Jean-Christophe Filliatre
+
+This software is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public
+License version 2.1, with the special exception on linking
+described in file LICENSE.
+
+This software is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+

headers/open-source/JCF_LGPL

+
+Copyright (C) Jean-Christophe Filliatre
+
+This software is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public
+License version 2.1, with the special exception on linking
+described in file LICENSE.
+
+This software is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+File modified by CEA (Commissariat à l'énergie atomique et aux
+                      énergies alternatives).
+