Add volatile keyword on shutdown

Change-Id: I7448507cf8f18036be6c25bf4ba9d5dd8c2ba768
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/manager.hpp b/manager.hpp
index d087b8b..24173e2 100644
--- a/manager.hpp
+++ b/manager.hpp
@@ -186,7 +186,7 @@
         }
 
         /** @brief Provided for testing only. */
-        bool _shutdown;
+        volatile bool _shutdown;
 
         /** @brief Path prefix applied to any relative paths. */
         const char* _root;