Remove unimplemented constructor in QTextEngine

QTextEngine(LayoutData*) declaration seems to have been added in
Qt 4.1 without an implementation. As far as I can see it has
never been implemented.

Change-Id: I4bbf032395f7c930c9e8d365cdbbcf47bb118d64
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>

src/gui/text/qtextengine_p.h

@@ -449,7 +449,6 @@ public:
 
     typedef QList<ItemDecoration> ItemDecorationList;
 
-    QTextEngine(LayoutData *data);
     QTextEngine();
     QTextEngine(const QString &str, const QFont &f);
     ~QTextEngine();