Added exception notice to all files.

libguile/strerror.c

@@ -16,7 +16,31 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with GNU Emacs; see the file COPYING.  If not, write to
 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
-Boston, MA 02111-1307, USA.  */
+Boston, MA 02111-1307, USA.
+
+As a special exception, the Free Software Foundation gives permission
+for additional uses of the text contained in its release of GUILE.
+
+The exception is that, if you link the GUILE library with other files
+to produce an executable, this does not by itself cause the
+resulting executable to be covered by the GNU General Public License.
+Your use of that executable is in no way restricted on account of
+linking the GUILE library code into it.
+
+This exception does not however invalidate any other reasons why
+the executable file might be covered by the GNU General Public License.
+
+This exception applies only to the code released by the
+Free Software Foundation under the name GUILE.  If you copy
+code from other Free Software Foundation releases into a copy of
+GUILE, as the General Public License permits, the exception does
+not apply to the code that you add in this way.  To avoid misleading
+anyone as to the status of such modified files, you must delete
+this exception notice from them.
+
+If you write modifications of your own for GUILE, it is your choice
+whether to permit this exception to apply to your modifications.
+If you do not wish that, delete this exception notice.  */
 
 /* Software engineering face-lift by Greg J. Badros, 11-Dec-1999,
    gjb@cs.washington.edu, http://www.cs.washington.edu/homes/gjb */