Most of the net/core/xxx sysctls are read-only now, but this
goal is achieved with excessive memory consumption in each
namespace - the whole table is cloned and most of the entries
in it are ~= 0222.

Split it into two parts and register (the largest) one at the
read-only root.
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>