ctest: Specify signal on test timeout

When tests timeout, ctest kills them. It would sometimes be interesting to get a stacktrace from where they are (to identify deadlocks). I don't currently see a way to do that.

On our (Travis) CI we can LD_PRELOAD libSegFault.so to intercept segfaults. From what I could see inm kwsysProcessKill it currently sends a KILL signal which cannot be intercepted by libSegFault.

It would be great if the signal to be sent on timeout could be specified when starting tests. I couldn't find the right place to put issues for kwsys, so this might be totally wrong here.

At the same time I still have some hope that someone here closes this because I was just missing a totally obvious alternative approach to achieve the goal.