add basic test case for readdir_r
add basic test case for readdir_r

Signed-off-by: Brian Chrisman <b6909212a30749694c836e4a7f37f34977709c1c@gmail.com>
Signed-off-by: Sage Weil <6dd34506bbd5e58221bbb3e4732d97c91f02277b@newdream.net>

ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph