Fix unused parameter.

*  src/tests/parse_print_test.cc: here.

src/tests/parse_print_test.cc

@@ -27,6 +27,8 @@ using namespace spot;
 
 int main(int argc, char** argv)
 {
+  (void) argc;
+  assert(argc == 2);
   int return_value = 0;
   kripke_parse_error_list pel;