QProgressDialog: remove unused QCursor member

The private member parentCursor was not populated since Qt4 times. This
lead to an unexpected behavior: When QProgressDialog::reset() was called
and value() was greater than 0, the cursor of the parent was set to a
default-constructed QCursor.
Therefore remove QProgressDialogPrivate::parentCursor.

Fixes: QTBUG-72660
Change-Id: I195688300e07ddbbb7c17a9f471513c542269c2a
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

src/widgets/dialogs/qprogressdialog.cpp

@@ -47,7 +47,6 @@
 #include "qapplication.h"
 #include "qstyle.h"
 #include "qpushbutton.h"
-#include "qcursor.h"
 #include "qtimer.h"
 #include "qelapsedtimer.h"
 #include <private/qdialog_p.h>
@@ -94,9 +93,6 @@ public:
     bool cancellation_flag;
     bool setValue_called;
     QElapsedTimer starttime;
-#ifndef QT_NO_CURSOR
-    QCursor parentCursor;
-#endif
     int showTime;
     bool autoClose;
     bool autoReset;
@@ -597,12 +593,6 @@ void QProgressDialog::setRange(int minimum, int maximum)
 void QProgressDialog::reset()
 {
     Q_D(QProgressDialog);
-#ifndef QT_NO_CURSOR
-    if (value() >= 0) {
-        if (parentWidget())
-            parentWidget()->setCursor(d->parentCursor);
-    }
-#endif
     if (d->autoClose || d->forceHide)
         hide();
     d->bar->reset();