Properly shut down test

tests/main/display_binding.c

@@ -38,6 +38,8 @@ int main(void)
 	if (ret == -ENODEV) return STARPU_TEST_SKIPPED;
 	STARPU_CHECK_RETURN_VALUE(ret, "starpu_init");
 
+	starpu_shutdown();
+
 	return EXIT_SUCCESS;
 }
 #endif