xenserver: Block until change in poll loop to avoid 100% CPU consumption.

Signed-off-by: Ben Pfaff <blp@nicira.com>

Author: blp

xenserver/usr_share_openvswitch_scripts_monitor-external-ids

@@ -188,6 +188,9 @@ def main(argv):
     interfaces = {}
     while True:
         if not idl.run():
+            poller = ovs.poller.Poller()
+            idl.wait(poller)
+            poller.block()
             continue
 
         new_bridges = {}