platforms problems

[Jimmy Zhuo]

> The failing tests are not even threading related. They test callback 
> functionality of the NCI interface. The reason for them to fail in the
threads 
> branch is that I changed the implementation of sleep() to use the timer 
> thread.
Well, rakudo doesn't use the NCI interface of Parrot. I wonder who else uses
parrot's nci interface on *BSD systems(or on linux/windows). I don't know
why it can't be marked as 'todo' test. And I can't understand why it's a
blocker too. Could someone explain it?