tty: Restore orphan slavery peers

In case if there is no master peer associated
with a slave peer we have two cases

 - the master peer was closed before slave
 - we just have no master peer at all, but
   only slave one

This patch addresses only first case -- we open
fake master and hook slaves on it, then close it
immediately.

The second case will be addressed later.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>