Don't pass ifioctls() through netmap - this has apparently been broken
since NETMAP_API 11 was introduced in February.  Since then, passing
ifioctls() through netmap results in netmap treating a struct ifreq
(or other ifioctl-related struct from net/if.h) as a struct nmreq,
looking deeply into it, and taking action based on the garbage it
finds there.

This is the root cause of sporadic failures of libuinet to
successfully bring up netmap interfaces and also appears to be the
root cause of some observed system crashes.