Parallelize the setup of plab vnodes alongside the loading of local physical nodes. We fork vnode_setup to operate on the plab vnodes just before firing off local reload/reboot/reconfig operations. The status of the plab vnode setup setup is checked just before firing off vnode_setup for any local vnodes. The ISUP wait for plab vnodes continues to fall within the same stage as wating for local vnodes. New arguments have been added to vnode_setup to tell it to only operate on specific vnode types. '-j' for local jail nodes, and '-p' for plab nodes. If neither are specified, the default is to operate on all types.