There's only a couple of things that are host-platform limited, i.e.,
security and process modes.
Everything else is specific to a target-platform. We can tell if we're
targeting a Linux platform, either on Linux or LCOW, by the presence of
the Linux key in the generated spec.
This doesn't introduce support for LCOW, as we'd need to plumb that down
from the caller. It will probably also need massaging to work with LCOW,
as some of the setup code here is probably incorrect for LCOW, e.g.,
the bind-mounts list may be incorrect.
Signed-off-by: Paul "TBBle" Hampson <Paul.Hampson@Pobox.com>