bge0: discard frame w/o packet header

[Kip Macy]

>
> The "discard frame w/o packet header" message comes from ether_input()
> if it gets an mbuf that doesn't have the M_PKTHDR flag set.  That
> can't happen unless something is very wrong with the system.  I'd like
> to make it a panic.  At least then the machine would reboot instead of
> just becoming unreachable.  Any objections?

Please don't make it the default. Odds are ifconfig down, ifconfig up
would fix it for those of us with console access. Either way it sounds
like someone has discovered a DOS in bge.

        -Kip