Strange race condition on Windows

[vanyle]

By adding an `echo` inside `threadFunc`, I can get it to crash every time:
    
    
    proc threadFunc(obj: Example) {.thread.} =
        withLock lock:
            echo "Inside thread"
            obj.s.add($obj.c)
            inc obj.c
    
    
    Run

Once again, this only occurs on windows.