Low: scheduler: respect shutdown locks when placing active resources
    
    Use new pe_resource_t members to indicate that a resource is locked to a
    particular node.
    
    For active resources (i.e. in the transition where the node is scheduled for
    shutdown), these are connected by checking each lockable resource for whether
    it is running on a single clean node that is shutting down.
    
    When applying constraints, place -INFINITY location constraints for locked
    resources on all nodes other than the lock node.
    
    (Inactive resources -- i.e. in later transitions after the node is shut down --
    are not yet locked.)