Update to a hopefully more future proof FSF address

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/exec-all.h b/exec-all.h
index f91e646..31ab7ad 100644
--- a/exec-all.h
+++ b/exec-all.h
@@ -14,8 +14,7 @@
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA  02110-1301 USA
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  */
 
 #ifndef _EXEC_ALL_H_