Relicense LGPL-2.0-only files to LGPL-2.0-or-later

All contributors allowed this change. The original files in Baloo were
also relicensed.

agent/priority.cpp

@@ -4,7 +4,7 @@
    Parts of this file are based on code from Strigi
    SPDX-FileCopyrightText: 2006-2007 Jos van den Oever <jos@vandenoever.info>
 
-   SPDX-License-Identifier: LGPL-2.0-only
+   SPDX-License-Identifier: LGPL-2.0-or-later
 */
 
 #include "priority.h"

agent/priority.h

 /* This file is part of the KDE Project
    SPDX-FileCopyrightText: 2008 Sebastian Trueg <trueg@kde.org>
 
-   SPDX-License-Identifier: LGPL-2.0-only
+   SPDX-License-Identifier: LGPL-2.0-or-later
 */
 
 #ifndef _NEPOMUK_LINUX_PRIORITY_H_