Validation for events/rooms in fed requests

When we get a federation request which refers to an event id, make sure that
said event is in the room the caller claims it is in.

(patch supplied by @turt2live)

synapse/federation/federation_server.py

@@ -425,6 +425,7 @@ class FederationServer(FederationBase):
             ret = yield self.handler.on_query_auth(
                 origin,
                 event_id,
+                room_id,
                 signed_auth,
                 content.get("rejects", []),
                 content.get("missing", []),