Golang allows to call methods on a nil object, as long as the methods
don't dereference the nil object. This is what we do here.
This makes all the userns configurations (idsPerPod or mapping configs
in /etc/subuid or /etc/subgid) to be ignored if the feature is off.
Signed-off-by: Rodrigo Campos <rodrigoca@microsoft.com>
b38d702807