qemu: change macvtap multicast list in response to NIC_RX_FILTER_CHANGED
    
    This patch adds functionality to processNicRxFilterChangedEvent().
    The old and new multicast lists are compared and the filters in
    the macvtap are programmed to match the guest's filters.
    
    Signed-off-by: Tony Krowiak <akrowiak@linux.vnet.ibm.com>