Fix genbuf/attach issue with specs

We were dropping off the spec for things like #l0.
ping.c

From NxM, ported to Akaros.
Skip the shitty e1000s on c89

The e1000s don't work with MSI.  One doesn't support it, and the other
flips out when MSI is used.  Those happen to be NICs l0 and l1.  Could
be more robust and fallback to l0 or something, etc.