Add lazy-pages and status-fd options
Add lazy-pages and status-fd options

This makes it possible to checkpoint using
[lazy-pages](https://criu.org/Lazy_migration). This also adds the option
to use a `StatusFile` to get notified as soon as the lazy-pages server
is ready.

Signed-off-by: Cyrill Troxler <c4607c028e91be530fc744538e26533ea2d00861@gmail.com>

containerd/go-runc,crosbymichael/go-runc