rework structure

hifive1-vp/hello/bsp/libwrap/sys/open.c

@@ -0,0 +1,9 @@
+/* See LICENSE of license details. */
+
+#include <errno.h>
+#include "stub.h"
+
+int __wrap_open(const char* name, int flags, int mode)
+{
+  return _stub(ENOENT);
+}