#2928 simgear 811f06 Add SPDX headers drops #ifndef

[Huntley Palmer]

It looks like simgear/package/Catalog.hxx had its #ifndef lines removed with the GPL licensing, causing build to fail.

Adding back:

// SPDX-License-Identifier: LGPL-2.1-or-later
// SPDX-FileCopyrightText: Copyright (C) 2013  James Turner - james@flightgear.org

#ifndef SG_PACKAGE_CATALOG_HXX
#define SG_PACKAGE_CATALOG_HXX

#pragma once

Lets the build finish

[James Turner]

Dropping the old style gaurd was intentional. It's the closing #endif that needed killed. BTW, it's better to report such 'real time' issues via the devel list, no ticket needed. Unless you promise to close once it's fixed (which it alreayd is....)