qmlls: move isSematicInfoOutdated to private object

this avoid use of the (still unintialized q->d) in settingsChanged in
the constructor

Change-Id: Idd756fc88df166124c34a6177a9d598604634057
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/qmljseditor/qmljseditordocument_p.h

@@ -48,6 +48,7 @@ public:
     void onDocumentUpdated(QmlJS::Document::Ptr doc);
     void reupdateSemanticInfo();
     void acceptNewSemanticInfo(const QmlJSTools::SemanticInfo &semanticInfo);
+    bool isSemanticInfoOutdated() const;
     void updateOutlineModel();
 
     void createTextMarks(const QList<QmlJS::DiagnosticMessage> &diagnostics);