build: include <config.h> from lib/yyerror.c

* lib/yyerror.c: Include <config.h>.
(cherry picked from commit cf33c228e0)

lib/yyerror.c

@@ -17,6 +17,7 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#include <config.h>
 #include <stdio.h>
 
 int yyerror (char const *);