tdf#120877: make menu items checkable as needed

Change-Id: I5a07526aa5187313977d6f7c244541be83b5edbc
Reviewed-on: https://gerrit.libreoffice.org/65930
Tested-by: Jenkins
Reviewed-by: Katarina Behrens <Katarina.Behrens@cib.de>
(cherry picked from commit 4de638c1)
Reviewed-on: https://gerrit.libreoffice.org/66747Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>

vcl/qt5/Qt5Menu.cxx

@@ -277,7 +277,10 @@ void Qt5Menu::CheckItem(unsigned nPos, bool bChecked)
         Qt5MenuItem* pSalMenuItem = GetItemAtPos(nPos);
         QAction* pAction = pSalMenuItem->getAction();
         if (pAction)
+        {
+            pAction->setCheckable(true);
             pAction->setChecked(bChecked);
+        }
     }
 }