Add wxUSE_MENUBAR build option, off by default in wxiOS

Allow building without wxMenuBar (but with wxMenu), as this class
doesn't exist and can't be reasonably implemented under iOS (but
wxMenu can and should be, as it's widely used in iOS 14 UI).

tests/events/propagation.cpp

@@ -436,10 +436,11 @@ wxMenu* CreateTestMenu(wxFrame* frame)
 {
     wxMenu* const menu = new wxMenu;
     menu->Append(wxID_APPLY);
+#if wxUSE_MENUBAR
     wxMenuBar* const mb = new wxMenuBar;
     mb->Append(menu, "&Menu");
     frame->SetMenuBar(mb);
-
+#endif
     return menu;
 }
 
@@ -464,10 +465,11 @@ void EventPropagationTestCase::MenuEvent()
 
     // Create a minimal menu bar.
     wxMenu* const menu = CreateTestMenu(frame);
+#if wxUSE_MENUBAR
     wxMenuBar* const mb = menu->GetMenuBar();
     wxScopedPtr<wxMenuBar> ensureMenuBarDestruction(mb);
     wxON_BLOCK_EXIT_OBJ1( *frame, wxFrame::SetMenuBar, (wxMenuBar*)NULL );
-
+#endif
     // Check that wxApp gets the event exactly once.
     ASSERT_MENU_EVENT_RESULT( menu, "aA" );
 
@@ -491,13 +493,14 @@ void EventPropagationTestCase::MenuEvent()
                           wxEvtHandler::SetNextHandler, (wxEvtHandler*)NULL );
     ASSERT_MENU_EVENT_RESULT_FOR( wxID_ABOUT, submenu, "aosomA" );
 
+#if wxUSE_MENUBAR
     // Test that the event handler associated with the menu bar gets the event.
     TestMenuEvtHandler hb('b'); // 'b' for "menu Bar"
     mb->PushEventHandler(&hb);
     wxON_BLOCK_EXIT_OBJ1( *mb, wxWindow::PopEventHandler, false );
 
     ASSERT_MENU_EVENT_RESULT( menu, "aomobA" );
-
+#endif
 
     // Also test that the window to which the menu belongs gets the event.
     TestMenuEvtHandler hw('w'); // 'w' for "Window"