fix: eventfd leak for v2 runtime with v1 cgroups
fix: eventfd leak for v2 runtime with v1 cgroups

There's no OOM monitoring for the v2 cgroups yet, so it seems unlikely
that there was a leak in that case.

Signed-off-by: Seth Pellegrino <c88f48088cadb870e5740609f00c774951e5136d@newrelic.com>

estesp/containerd,crosbymichael/containerd,estesp/containerd,containerd/containerd,dmcgowan/containerd,thaJeztah/containerd,containerd/containerd,dmcgowan/containerd,thaJeztah/containerd,mikebrow/containerd,crosbymichael/containerd,vdemeester/containerd,vdemeester/containerd,mikebrow/containerd