The current implementation of AF_PACKET only uses the
device name and protocol options even when a 5-tuple of
Device, Protocol, Packet Type, Hardware Type, and
Hardware Address are supplied.  I needed
socket.sendto() to support sending to a Hardware
Address, so this patch supports such functionality.

The length check on the hardware address is hard coded
to 8 since that is the value used in the sockaddr_ll
struct.

I'm not that familiar with the Python internals, so
s->errorhandler() may not be the best call to make for
an invalid hardware address length.