Add flag to lxcBasicMounts to control use in user namespaces
    
    Some mounts must be skipped if running inside a user namespace,
    since the kernel forbids their use. Instead of strcmp'ing the
    filesystem type in the body of the loop, set an explicit flag
    in the lxcBasicMounts table.
    
    Signed-off-by: Daniel P. Berrange <berrange@redhat.com>