_ipaddr_info monkey_patch breaks UDP

[jordens]

The monkey patch from #506 (1c32d4f) breaks UDP.
This in turn breaks pc_rpc device controllers that use UDP.

# python 3.5.3
import asyncio
import artiq.monkey_patches

loop = asyncio.get_event_loop()
loop.run_until_complete(loop.create_datagram_endpoint(
                object, remote_addr=("127.0.0.1", 4000)))

Traceback (most recent call last):
  File "test_monkey.py", line 6, in <module>
    object, remote_addr=("127.0.0.1", 4000)))
  File "/home/rj/src/conda/envs/py35/lib/python3.5/asyncio/base_events.py", line 466, in run_until_complete
    return future.result()
  File "/home/rj/src/conda/envs/py35/lib/python3.5/asyncio/futures.py", line 293, in result
    raise self._exception
  File "/home/rj/src/conda/envs/py35/lib/python3.5/asyncio/tasks.py", line 241, in _step
    result = coro.throw(exc)
  File "/home/rj/src/conda/envs/py35/lib/python3.5/asyncio/base_events.py", line 932, in create_datagram_endpoint
    raise exceptions[0]
  File "/home/rj/src/conda/envs/py35/lib/python3.5/asyncio/base_events.py", line 919, in create_datagram_endpoint
    yield from self.sock_connect(sock, remote_address)
  File "/home/rj/src/conda/envs/py35/lib/python3.5/asyncio/selector_events.py", line 446, in sock_connect
    yield from resolved
  File "/home/rj/src/conda/envs/py35/lib/python3.5/asyncio/futures.py", line 380, in __iter__
    yield self  # This tells Task to wait for completion.
  File "/home/rj/src/conda/envs/py35/lib/python3.5/asyncio/tasks.py", line 304, in _wakeup
    future.result()
  File "/home/rj/src/conda/envs/py35/lib/python3.5/asyncio/futures.py", line 293, in result
    raise self._exception
  File "/home/rj/src/conda/envs/py35/lib/python3.5/concurrent/futures/thread.py", line 55, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/home/rj/src/conda/envs/py35/lib/python3.5/socket.py", line 733, in getaddrinfo
    for res in _socket.getaddrinfo(host, port, family, type, proto, flags):
socket.gaierror: [Errno -7] ai_socktype not supported

[sbourdeauducq]

At some point the asyncio is calling:
loop.getaddrinfo("127.0.0.1", 4000, family=socket.AF_INET, type=socket.SOCK_STREAM, proto=17, flags=0)
which raises the exception and which I suspect is another Python bug that is exposed by the patch.

[sbourdeauducq]

i.e. asyncio is asking for a stream UDP (proto=17) address, which is obviously not possible. Without the patch, the error is masked, as _ipaddr_info disregards the type/proto combination.

[jordens]

thanks!