A domainname field was recently added to the OCI spec. Prior to this
folks would need to set this with a sysctl, but now runtimes should be
able to setdomainname(2). There's an open change to runc at the moment
to add support for this so I've just left testing as a couple spec
validations in CRI until that's in and usable.
Signed-off-by: Danny Canter <danny@dcantah.dev>