Generic code for mbuf(9) queues.

[glebius]

Summary

Provide a bunch of functions that implement a basic mbuf queue, based on queue(3)
glue. The new code is provided to substitute struct ifqueue in facilities, that
actually are not interfaces: e.g. multicast handling routines. It also substitutes
home-grown implementation in cxgb(4) and Xen netfront. It might be there are more
places, where the code can be used instead of local implementation.

[jonlooney_gmail.com]

Wasn't much of this already committed in r278977? If so, it seems like this review can be closed.

[emaste]

Ping?

[glebius]

Committed years ago.