Don't attempt to uncheck menu radio item in wxGTK

Unchecking radio item makes no sense and wxMSW does nothing in this case, so
don't do anything in wxGTK neither, in particular don't generate a spurious
wxEVT_MENU.

Closes #17318.

src/gtk/menu.cpp

@@ -684,18 +684,23 @@ void wxMenuItem::Check( bool check )
     if (check == m_isChecked)
         return;
 
-    wxMenuItemBase::Check( check );
-
     switch ( GetKind() )
     {
-        case wxITEM_CHECK:
         case wxITEM_RADIO:
+            // It doesn't make sense to uncheck a radio item.
+            if ( !check )
+                return;
+
+            wxFALLTHROUGH;
+        case wxITEM_CHECK:
             gtk_check_menu_item_set_active( (GtkCheckMenuItem*)m_menuItem, (gint)check );
             break;
 
         default:
             wxFAIL_MSG( wxT("can't check this item") );
     }
+
+    wxMenuItemBase::Check( check );
 }
 
 void wxMenuItem::Enable( bool enable )