QNX: Fix compiler warning by when FEATURE_clipboard is not enabled

warning: unused parameter 'selectionClipboard' [-Wunused-parameter]

Pick-to: 6.2 6.3 5.15
Task-number: QTBUG-101382
Change-Id: I4f42a6f41c8f8a8b3edd3a042c89b7a2a49a96fe
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>

src/widgets/widgets/qwidgettextcontrol.cpp

@@ -940,6 +940,8 @@ void QWidgetTextControl::setTextCursor(const QTextCursor &cursor, bool selection
 #ifndef QT_NO_CLIPBOARD
     if (selectionClipboard)
         d->setClipboardSelection();
+#else
+    Q_UNUSED(selectionClipboard);
 #endif
 }