asyncio: sync with Tulip

* _WaitHandleFuture.cancel() now notify IocpProactor through the overlapped
  object that the wait was cancelled.
* Optimize IocpProactor.wait_for_handle() gets the result if the wait is
  signaled immediatly.
* Enhance representation of Future and Future subclasses

  - Add "created at filename:lineno" in the representation
  - Add Future._repr_info() method which can be more easily overriden than
    Future.__repr__(). It should now be more easy to enhance Future
    representation without having to modify each subclass. For example,
    _OverlappedFuture and _WaitHandleFuture get the new "created at" information.
  - Use reprlib to format Future result, and function arguments when formatting a
    callback, to limit the length of the representation.

* Fix repr(_WaitHandleFuture)
* _WaitHandleFuture and _OverlappedFuture: hide frames of internal calls in the
  source traceback.
* Cleanup ProactorIocp._poll(): set the timeout to 0 after the first call to
  GetQueuedCompletionStatus()
* test_locks: close the temporary event loop and check the condition lock
* Remove workaround in test_futures, no more needed

Lib/test/test_asyncio/test_locks.py

@@ -660,10 +660,13 @@ class ConditionTests(test_utils.TestCase):
         lock = asyncio.Lock(loop=self.loop)
         cond = asyncio.Condition(lock, loop=self.loop)
 
-        self.assertIs(lock._loop, cond._loop)
+        self.assertIs(cond._lock, lock)
+        self.assertIs(cond._loop, lock._loop)
 
     def test_ambiguous_loops(self):
         loop = self.new_test_loop()
+        self.addCleanup(loop.close)
+
         lock = asyncio.Lock(loop=self.loop)
         with self.assertRaises(ValueError):
             asyncio.Condition(lock, loop=loop)