Most NFSv4 servers implement AUTH_UNIX, and administrators will
prefer this over AUTH_NULL. It is harmless for our client to try
this flavor in addition to the flavors mandated by RFC 3530/5661.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>