In particular add support for the new controllers:

* perf_event (nothing here, but may be used by the perf tool so we should
  keep it)
* net_cls
* net_prio
* pids

Also add support for many more memory properties that were not implemented
in the first pass, but the container may use.

Note that this commit omits the "devices" controller, because that needs to
be checkpointed and restored in a special way.
Signed-off-by: Tycho Andersen <tycho.andersen@canonical.com>
CC: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>