commit 507cee36 moved the close and re-open of fds 0-2 into
do_start.  But this means that the lxc monitor itself keeps the
caller's fds 0-2 open, which is wrong for daemonized containers.

Closes #548
Reported-by: Mathieu Le Marec - Pasquet <kiorky@cryptelium.net>
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>