Encode the AUTH flavour in the clientid, since AUTH_UNIX and AUTH_GSS
 credentials will always conflict.

 Then, strategy is to first retry after sleeping for a lease period. If
 the server then still refuses our clientid, assume we have a conflicting
 client, out there, and try bumping a "uniquifier" variable.

 Give up if we're signalled, or if we've gone through the entire range
 of uniquifiers...
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>