Non-opened control terminal

* Set a control terminal
* Close a file descriptor on it
* Dump/restore
* Open the control terminal (/dev/tty)
* Check, that it connected to the master end
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>