These functions are all unnecessary now, and they only have meaning in the M:N
context. Removing these functions uncovered a bug in the librustuv timer
bindings, but it was fairly easy to cover (and the test is already committed).
These cannot be completely removed just yet due to their usage in the WaitQueue
of extra::sync, and until the mutex in libextra is rewritten it will not be
possible to remove the deferred sends for channels.
This is a very real problem with cvars on normal systems, and all of channels
will not work if spurious wakeups are accepted. This problem is just solved with
a synchronized flag (accessed in the cvar's lock) to see whether a signal()
actually happened or whether it's spurious.
There was a race in the code previously where schedulers would *immediately*
shut down after spawning the main task (because the global task count would
still be 0). This fixes the logic by blocking the sched pool task in receving on
a port instead of spawning a task into the pool to receive on a port.
The modifications necessary were to have a "simple task" running by the time the
code is executing, but this is a simple enough thing to implement and I forsee
this being necessary to have implemented in the future anyway.
