Update ocgcore/libdebug.cpp

include string.h header, it will be not included automatically under Linux/gcc, and cause an error.

ocgcore/libdebug.cpp

@@ -5,6 +5,7 @@
  *      Author: Argon
  */
 
+#include <string.h>
 #include "scriptlib.h"
 #include "duel.h"
 #include "field.h"