Otherwise we will see warnings like these ones:
Warn  (criu/kerndat.c:805): Can't load /run/criu.kdat
Warn  (criu/net.c:2726): Unable to get a socket network namespace
Warn  (criu/kerndat.c:844): Can't keep kdat cache on non-tempfs
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>