vmm/virtualbox: Make MachineFile and VboxCompat new-style classes
vmm/virtualbox: Make MachineFile and VboxCompat new-style classes

- Convert class definitions to new-style Python classes

cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr