[CRITICAL] KIO Test "threadtest" can enter into infinite loop

[Ben Cooksley]

Hi all,

It appears the test running with the binary name of "threadtest" in
kio has a grave bug which can lead to it entering into an infinite
loop.

This was consuming virtually the entire resources of one builder with
old hung processes, and the whole core of another builder -
drastically limiting the capabilities of the CI system (even though
KIO was not being built at the time).

Can someone please investigate? Manual intervention (with kill -9) is
needed to remove these hung processes.

Thanks,
Ben