Qualify a field name in NotificationQueueTest

Summary: MSVC currently has a bug that causes it to incorrectly resolve it to `std::queue`: https://developercommunity.visualstudio.com/content/problem/2342/c-failure-to-resolve-instance-member-in-lambda-con.html

Reviewed By: lbrandy

Differential Revision: D4187256

fbshipit-source-id: 207eafa339f7255ae881d8ab80f4847222c3b8c9

folly/io/async/test/NotificationQueueTest.cpp

@@ -81,7 +81,7 @@ void QueueTest::sendOne() {
   // Start a new EventBase thread to put a message on our queue
   ScopedEventBaseThread t1;
   t1.getEventBase()->runInEventBaseThread([&] {
-    queue.putMessage(5);
+    this->queue.putMessage(5);
   });
 
   // Loop until we receive the message