licensing: Add LGPL-2.1-or-later short identifier as a LGPLv2+ variant
    
    The SPDX license short identifier for "GNU Lesser General Public License
    v2.1 or later" is LGPL-2.1-or-later [0]. Add a SPDX to Fedora mapping.
    
    [0]: https://spdx.org/licenses/LGPL-2.1-or-later.html