Additional readdir cookie loop information

Print out the name of the file that triggers the cookie loop  message to
make it slightly easier to track down the cause.

Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
‚†©Ý“5x