Now crtools checks address, but it may be zero. For example,
a listen socket is bound to zero address to accept connections
from any addresses.

v2: add a comment about zero port
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>