CppTools: Do not hand over partly reloaded files to the code model

When a reloading operation was in progress, CppEditorSupport::contents()
could return a partly reloaded file to the code model leading to parse
errors and incomplete highlighting.

Fixed by checking if the file is currently being reloaded.

Task-number: QTCREATORBUG-9382

Change-Id: Iee97e10444763c0cbf481132afa4617c5cdbd15c
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>

src/plugins/cpptools/cpptoolseditorsupport.h

@@ -121,6 +121,9 @@ signals:
 private slots:
     void onMimeTypeChanged();
 
+    void onAboutToReload();
+    void onReloadFinished();
+
     void updateDocument();
     void updateDocumentNow();
 
@@ -166,6 +169,7 @@ private:
     // content caching
     mutable QString m_cachedContents;
     mutable int m_cachedContentsEditorRevision;
+    bool m_fileIsBeingReloaded;
 
     QTimer *m_updateEditorTimer;
     EditorUpdates m_editorUpdates;