When kmem accounting switched from account by default to only account if
flagged by __GFP_ACCOUNT, IPC mqueue and messages was left out.
The production use case at hand is that mqueues should be customizable
via sysctls in Docker containers in a Kubernetes cluster. This can only
be safely allowed to the users of the cluster (without the risk that
they can cause resource shortage on a node, influencing other users'
containers) if all resources they control are bounded, i.e. accounted
for.