pc_rpc: use ProactorEventLoop on Windows (#627)

artiq/protocols/pc_rpc.py

@@ -11,6 +11,7 @@ client passes a list as a parameter of an RPC method, and that method
 client's list.
 """
 
+import os
 import socket
 import asyncio
 import threading
@@ -580,6 +581,10 @@ def simple_server_loop(targets, host, port, description=None):
 
     See ``Server`` for a description of the parameters.
     """
+    if os.name == "nt":
+        loop = asyncio.ProactorEventLoop()
+        asyncio.set_event_loop(loop)
+    else:
         loop = asyncio.get_event_loop()
     try:
         server = Server(targets, description, True)