tdf#120453 Preserve literal '&' in Qt menu texts

As described in the QMenuBar documentation,
a single ampersand in a menu item text is used to
set the shortcut for the menu, while "&&" is used to
get a real ampersand character.

Change-Id: Idf510641c8919ff8223114413851cb3ee7d7b4a2
Reviewed-on: https://gerrit.libreoffice.org/62405
Tested-by: Jenkins
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>

vcl/qt5/Qt5Menu.cxx

@@ -250,7 +250,13 @@ void Qt5Menu::slotMenuTriggered(Qt5MenuItem* pQItem)
     }
 }
 
-void Qt5Menu::NativeItemText(OUString& rItemText) { rItemText = rItemText.replace('~', '&'); }
+void Qt5Menu::NativeItemText(OUString& rItemText)
+{
+    // preserve literal '&'s in menu texts
+    rItemText = rItemText.replaceAll("&", "&&");
+
+    rItemText = rItemText.replace('~', '&');
+}
 
 Qt5MenuItem::Qt5MenuItem(const SalItemParams* pItemData)
     : mpParentMenu(nullptr)