Log Message:
Add iperf3 as version 3.0.11.

Iperf3 is a tool for active measurements of the maximum achievable
bandwidth on IP networks.  It supports tuning of various parameters
related to timing, protocols, and buffers.  For each test it reports
the bandwidth, loss, and other parameters.

This version, sometimes referred to as iperf3, is a redesign of an
original version developed at NLANR/DAST.  iperf3 is a new
implementation from scratch, with the goal of a smaller, simpler code
base, and a library version of the functionality that can be used in
other programs. Iperf3 also has a number of features found in other tools
such as nuttcp and netperf, but were missing from the original iperf.
These include, for example, a zero-copy mode and optional JSON output.
Note that iperf3 is NOT backwards compatible with the original iperf.