Add missing includes for QPointer

qtbase removed some indirect include somewhere.

Change-Id: I477e6dccebda4fbb81f6fffd179115840c67002f
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/qmlprojectmanager/qmlproject.h

@@ -7,6 +7,8 @@
 #include "qmlprojectmanager_global.h"
 #include <projectexplorer/project.h>
 
+#include <QPointer>
+
 namespace QmlProjectManager {
 
 class QmlProject;