Change the append_clientaddr_option() function to support sending either

IPv4 or IPv6 addresses to the kernel via the "clientaddr=" option.

If the mount.nfs4 command can't determine an appropriate callback address,
it used to fail the mount request.  This new function simply sends an ANY
address instead, so the mount request succeeds, but delegation is disabled.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Steve Dickson <steved@redhat.com>