Ok, I've stopped C-Reduce from explicitly deleting its temp dirs.
This seems to fix all of the stupid races that I had put in.During a long reduction, a few thousand dirs will get created, but they should all get cleaned up automatically when the main C-Reduce process exits. If this bothers anyone, let me know and maybe we can do something smarter, but I'm happy with this solution. Don't do testcase reduction if you don't have some free space in /tmp :).
John
