Fix build

Author: nyalldawson

python/gui/attributetable/qgsfeaturemodel.sip

@@ -4,6 +4,6 @@ class QgsFeatureModel
 #include <qgsfeaturemodel.h>
 %End
   public:
-    virtual ~QgsFeatureModel() {}
+    virtual ~QgsFeatureModel();
     virtual QModelIndex fidToIndex( QgsFeatureId fid ) = 0;
 };