common/Determinism.v: dual-license with GPL

There was no good reason why Determinism.v was the only file in common/ that was not dual-licensed (GPL + noncommercial).  Plus, it simplifies the wording of the LICENSE file.

Author: xavierleroy

LICENSE

@@ -24,20 +24,7 @@ option) any later version:
 
   all files in the lib/ directory
 
-  common/AST.v
-  common/Behaviors.v
-  common/Errors.v
-  common/Events.v
-  common/Globalenvs.v
-  common/Linking.v
-  common/Memdata.v
-  common/Memory.v
-  common/Memtype.v
-  common/Smallstep.v
-  common/Subtyping.v
-  common/Switch.v
-  common/Unityping.v
-  common/Values.v
+  all files in the common/ directory
 
   cfrontend/Clight.v
   cfrontend/ClightBigstep.v

common/Determinism.v

@@ -6,6 +6,9 @@
 (*                                                                     *)
 (*  Copyright Institut National de Recherche en Informatique et en     *)
 (*  Automatique.  All rights reserved.  This file is distributed       *)
+(*  under the terms of the GNU General Public License as published by  *)
+(*  the Free Software Foundation, either version 2 of the License, or  *)
+(*  (at your option) any later version.  This file is also distributed *)
 (*  under the terms of the INRIA Non-Commercial License Agreement.     *)
 (*                                                                     *)
 (* *********************************************************************)