Fixup the last commit so newer-style linux shaping with netem works.
I didn't know this initially, but it turns out that with newer netems, you can't add another netem qdisc instance (nor an htb instance) inside another netem instance. The linux maintainers removed "classful" qdisc support from the netem qdisc (which makes it possible for another qdisc to be "nested" inside a netem qdisc) because 1) netem couldn't even nest an instance of itself inside itself -- which isn't stricly necessary for us because we can do both delay and plr in one netem instance), and 2) because apparently non-work-conserving qdiscs already didn't work inside netem (a work-conserving qdisc is one that always has a packet ready when its underlying device is ready to transmit a packet -- thus, a bandwidth-shaping qdisc that might not have a packet ready because it's slowing down the send rate is non-work-conserving), and 3) to support code cleanups. So -- what this means for us is that by using modern netem, we are now doing bandwidth shaping first, then plr and delay. With our old custom kernel modules, we were doing plr, delay, then bandwidth. I talked this strategy over with Jon (because adding classful support back to netem is nontrivial and defeats the point of trying to use what's in the kernel directly without patching it more), and we believe it's ok to do -- one because it doesn't always change the shaped rate from the old way we used to do things, and second because using these params *in tandem* to do link shaping is kind of a poor man's way of actually modeling real link behavior -- a la flexlab. So we'll just document it for users, call it beta for now, and test it against the old way and BSD. If it looks reasonable, we'll stick with it; otherwise we'll look at reviving the old style.
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