oo-accept-node changed the cgroups check to ignore defunct processes

Changed the oo-accept-node cgroups check to ignore defunct processes as these
processes can't consume any resources, so it's normal for the kernel to remove
them from cgroups.
Merge pull request #2556 from twiest/dev/twiest/oo-accept-node/cgroups-defunct-procs

Merged by openshift-bot