Log Message:
iperf3: updated to 3.16

iperf-3.16 2023-11-30
---------------------

* Notable user-visible changes

  * Multiple test streams started with -P/--parallel will now be
    serviced by different threads. This allows iperf3 to take
    advantage of multiple CPU cores on modern processors, and will
    generally result in significant throughput increases.

  * OpenSSL 3 is now detected at build time. If OpenSSL 3 is found,
    various older, deprecated, APIs will not be used. iperf3 will
    continue to work with OpenSSL 1.1.1. OpenSSL is used as a part
    of the iperf3 authentication functionality.

  * The authorized users file used by the authentication functionality
    is now checked for accessibility much earlier during the program
    startup, as opposed to being checked near the start of a
    tes.

* Developer-visible changes

  * BREAKING CHANGE: iperf3 now requires pthreads and C atomic
    variables to compile and run.