Merge with Python 3.4 (asyncio)

- Close #22063: socket operations (socket,recv, sock_sendall, sock_connect,
  sock_accept) now raise an exception in debug mode if sockets are in blocking
  mode.
- asyncio: Use the new os.set_blocking() function of Python 3.5 if available

diff --cc Lib/asyncio/unix_events.py
Simple merge

diff --cc Lib/test/test_asyncio/test_events.py
Simple merge