We need to do two non-trivial things with ttys -- interconnect
slaves to masters (or to each other) and setup ctl-tty restoring
task.

Now this is done in subsequently depending on each other steps:

1. collect ttys
2. interconnect slaves and mark ctl-tty tasks
3. collect fake fds for tty-ctl tasks
4. setup orphaned slaves

We can relax this logic in two ways:

1. don't split marking ctl-tty tasks and then creating fds for them
   do it in one step at the end
2. don't interconnect slaves with masters and orphaned slaves in
   two steps -- do it in one place after fds are collected
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>