Replace readdir_r to readdir to fix build error

Replace readdir_r to readdir to fix build error

 [Problem] After update tool chain to GCC6, 'readdir_r is deprecated' build error happen

'readdir_r' is deprecated because of below reasons.
 *  On systems where NAME_MAX is undefined, calling readdir_r() may be
    unsafe because the interface does not allow the caller to specify
    the length of the buffer used for the returned directory entry.

 *  On some systems, readdir_r() can't read directory entries with
    very long names.  When the glibc implementation encounters such a
    name, readdir_r() fails with the error ENAMETOOLONG after the
    final directory entry has been read.  On some other systems,
    readdir_r() may return a success status, but the returned d_name
    field may not be null terminated or may be truncated.

Change-Id: Iaeabf4b09ab77dfedbc161c725c27a39ec4325c2
Signed-off-by: jiyong.min <jiyong.min@samsung.com>