fix access-after-free bug in ProducerConsumerQueueTest

Summary: This bug causes failure when the test is run under ASAN.

Reviewed By: meyering

Differential Revision: D3229494

fb-gh-sync-id: a43c8332cc45f7892ac86cd0abb799616bca7779
fbshipit-source-id: a43c8332cc45f7892ac86cd0abb799616bca7779

folly/test/ProducerConsumerQueueTest.cpp

@@ -160,11 +160,11 @@ struct CorrectnessTest {
         } else {
           goto again;
         }
+        EXPECT_EQ(*data, expect);
       } else {
+        EXPECT_EQ(*data, expect);
         queue_.popFront();
       }
-
-      EXPECT_EQ(*data, expect);
     }
   }