vfs: add directory APIs

components/newlib/include/sys/dirent.h

@@ -1,13 +0,0 @@
-/* <dirent.h> includes <sys/dirent.h>, which is this file.  On a
-   system which supports <dirent.h>, this file is overridden by
-   dirent.h in the libc/sys/.../sys directory.  On a system which does
-   not support <dirent.h>, we will get this file which uses #error to force
-   an error.  */
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-#error "<dirent.h> not supported"
-#ifdef __cplusplus
-}
-#endif