Add constructor/destructor to stats_manager

This ensures m_total is properly initialized.

Signed-off-by: Mark Stemm <mark.stemm@gmail.com>

userspace/engine/stats_manager.h

@@ -27,6 +27,9 @@ limitations under the License.
 class stats_manager
 {
 public:
+	stats_manager();
+	virtual ~stats_manager();
+
 	/*!
 		\brief Erases the internal state and statistics data
 	*/