The option is -r|--pivot-root and an argument is a path to new root.
A root task will make pivot_root. LXC CT does that, so we need that
for restoring.

v2: s/pivot-root/root/
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>