fix incorrect LGPL version tags

Circular_kernel_2/benchmark/parser/benchmark_parser.cpp

@@ -16,7 +16,11 @@
    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor,
-   Boston, MA 02110-1301, USA.  */
+   Boston, MA 02110-1301, USA.  
+
+   SPDX-License-Identifier: LGPL-2.0+
+
+*/
 
 /* As a special exception, when this file is copied by Bison into a
    Bison output file, you may use that output file without restriction.