numa: Introduce MachineClass::auto_enable_numa for implicit NUMA node

Add MachineClass::auto_enable_numa field. When it is true, a NUMA node
is expected to be created implicitly.

Acked-by: David Gibson <david@gibson.dropbear.id.au>
Suggested-by: Igor Mammedov <imammedo@redhat.com>
Suggested-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Tao Xu <tao3.xu@intel.com>
Message-Id: <20190905083238.1799-1-tao3.xu@intel.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
3 files changed