Add SPDX license headers for LGPL-2.1-or-later to various files

These have all been added manually, as I’ve finished all the files which
I can automatically detect.

All the license headers in this commit are for LGPL-2.1-or-later, and
all have been double-checked against the license paragraph in the file
header.

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>

Helps: #1415

gmodule/gmodule-ar.c

@@ -1,6 +1,8 @@
 /* GMODULE - GLIB wrapper code for dynamic module loading
  * Copyright (C) 1998, 2000 Tim Janik
  *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either

gmodule/gmodule-dl.c

@@ -1,6 +1,8 @@
 /* GMODULE - GLIB wrapper code for dynamic module loading
  * Copyright (C) 1998, 2000 Tim Janik
  *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either

gmodule/gmodule-win32.c

@@ -4,6 +4,8 @@
  * Win32 GMODULE implementation
  * Copyright (C) 1998 Tor Lillqvist
  *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either

gmodule/gmodule.c

@@ -1,6 +1,8 @@
 /* GMODULE - GLIB wrapper code for dynamic module loading
  * Copyright (C) 1998 Tim Janik
  *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either

gmodule/gmodule.h

@@ -1,6 +1,8 @@
 /* GMODULE - GLIB wrapper code for dynamic module loading
  * Copyright (C) 1998 Tim Janik
  *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either

gmodule/gmoduleconf.h.in

@@ -1,6 +1,8 @@
 /* GMODULE - GLIB wrapper code for dynamic module loading
  * Copyright (C) 1998 Tim Janik
  *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either

gmodule/tests/cxx.cpp

@@ -1,4 +1,6 @@
 /* Copyright (C) 2001 Sebastian Wilhelmi <wilhelmi@google.com>
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public

gmodule/tests/libmoduletestplugin_a.c

@@ -1,6 +1,8 @@
 /* libgplugin_a.c - test plugin for testgmodule
  * Copyright (C) 1998 Tim Janik
  *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either

gmodule/tests/libmoduletestplugin_b.c

@@ -1,6 +1,8 @@
 /* libgplugin_b.c - test plugin for testgmodule
  * Copyright (C) 1998 Tim Janik
  *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either

gmodule/tests/module-test.c

@@ -1,6 +1,8 @@
 /* module-test.c - test program for GMODULE
  * Copyright (C) 1998 Tim Janik
  *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either