QTabBar: Fix crash when the tab being dragged is deleted programmatically.

Call QTabBarPrivate::moveTabFinished() from QTabBar::removeTab()
to cancel any drag in progress to prevent crashes due
to invalidated indexes.

Task-number: QTBUG-52527
Change-Id: I5bd8cc6f55e5aea1f1a4710494ba5b92939a42ee
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

src/widgets/widgets/qtabbar.cpp

@@ -897,6 +897,9 @@ void QTabBar::removeTab(int index)
 {
     Q_D(QTabBar);
     if (d->validIndex(index)) {
+        if (d->dragInProgress)
+            d->moveTabFinished(d->pressedIndex);
+
 #ifndef QT_NO_SHORTCUT
         releaseShortcut(d->tabList.at(index).shortcutId);
 #endif