[LEDE-DEV] [PATCH] iperf3: update to version 3.1.5 and download via git

[Dave Täht]

Could you verify this version has a working -S Qos option? It took it,
but didn't actually set it in the packets, misleading a lot of people.

There's a pull request on github outstanding to improve, that adding a
dscp option....

See also:

http://burntchrome.blogspot.com/2016/09/iperf3-and-microbursts.html

I think the patches for that were only partially taken up.