crtools: close all desriptors only for the root task

For all other tasks only unsed service descriptors will be closed.

This change allows to have file descriptors, which may be used for
restoring namespaces. All non-server descriptors must be closed before
restoring files.

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
proc_parse: parse fdinfo to get pos and flags

We are going to parse fdinfo for getting mnt_id,
so we can take there pos and flags and don't call
fcntl and lseek for that.

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
proc_parse: parse mnt_id from /proc/PID/fdinfo/FD

It will be used for restoring files from proper mounts.

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>