Similar to f444f7fac40, we need to treat memory.oom_control as a "special"
property and try not to write its default value, since in the 3.11 kernel
it can't be written when memory.use_heirarchy is true, which is the
default.

CC: Andrei Vagin <avagin@virtuozzo.com>
Signed-off-by: Tycho Andersen <tycho.andersen@canonical.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>