Windows diverter unassigned local variable usage

[strictlymike]

FakeNet's PyDivert exception handling in windows.py mixes and matches local variable names for the user-friendly protocol description (protocol vs. proto) resulting in a UnboundLocalError being raised due to proto being referenced before assignment in error cases involving ICMP.

                    protocol = 'Unknown'

                    if pkt.proto:
                        protocol = pkt.proto
                    elif pkt.is_icmp:
                        proto = 'ICMP'

                    self.logger.error('ERROR: Failed to send %s %s %s packet',
                                      self.pktDirectionStr(pkt),
                                      self.pktInterfaceStr(pkt), proto)

The variable usage needs to be made consistent to prevent the exception.