QmlDesigner: Fix compile with Qt 5.10

The QtQuick include at this point for some reasons tries to
include not existing Vulcan headers.

Change-Id: Ie2dc667b3438a2bbf7e8f251520502a836b109db
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/qmldesigner/components/itemlibrary/itemlibrarymodel.h

@@ -28,7 +28,7 @@
 #include <QMap>
 #include <QIcon>
 #include <QAbstractListModel>
-#include <QtQuick>
+#include <QtQml/qqml.h>
 
 QT_FORWARD_DECLARE_CLASS(QMimeData)
 

src/plugins/qmldesigner/components/itemlibrary/itemlibrarywidget.cpp

@@ -41,6 +41,7 @@
 #include <metainfo.h>
 #include "rewritingexception.h"
 
+#include <QDrag>
 #include <QFileInfo>
 #include <QFileSystemModel>
 #include <QStackedWidget>
@@ -54,6 +55,7 @@
 #include <QApplication>
 #include <QTimer>
 #include <QShortcut>
+#include <QQmlContext>
 #include <QQuickItem>
 
 namespace QmlDesigner {