The run loop will be kept alive because it has an `AsyncTask`. We
also can simple stop the loop with `uv_stop()`.
The `RunLoop` is still gonna be the last object to be destroyed
because it is the first object to be created in the thread, so
by design it won't outlive `Timer`s and `AsyncTask`s.
This patch won't change the current behavior, will just make
the code simpler.
Should not be used at all, added for a corner case
on OSX network backend where the request is processed on
a worker thread managed by OSX and we need to wait for
that reply before destroying the thread that pushed the
request.
