tracertstats is not entirely realtime on FreeBSD

[salcock]

When running tracertstats -i 1 on FreeBSD with more than one processing thread, output tends to appear in bursts of several lines appearing at multiple second intervals rather than the one line per second that would be expected.

Attaching truss to the running process seems to make the program behave correctly again, so it is a bit hard to get visibility into what is going on.

Program also runs fine if only one processing thread is used (i.e. -t 1 on the CLI).

Adding a specific "fflush(stdout);" to the output function doesn't change anything, so it doesn't appear to be a stdio buffering issue.