license: fix and add SPDX license identifiers and drop license comments

This also fixes a few wrong SPDX license identifiers, where the original
license comment indicates GPL-2.0-only.

This is not done manually, but by running the following script:

---

    #!/bin/bash

    # Tool to drop license comments, adding SPDX license identifiers, while preserving
    # copyright comments. The point is not to manually do this task, but perform some
    # hacked up string replacement.

    _cp() {
        /bin/cp "$@"
    }

    _cat() {
        /bin/cat "$@"
    }

    in_file() {
        local T=$(mktemp)

        _cp -f "$1" "$T"
        _cat "$T"
        rm -f "$T"
    }

    out_file() {
        local T=$(mktemp)

        _cat - > "$T"
        _cp -f "$T" "$1"
        rm -f "$T"
    }

    join() {
        _cat "$@" | awk '{ printf("%s#x#", $0)}'
    }

    unjoin() {
        _cat - | sed 's/#x#/\n/g'
    }

    files_all() {
        git ls-files |
        grep -v '\.png$' |
        grep -v '^include/linux-private/'
    }

    adjust() {
         NEWLINES='\(#x#\)\+'
         COPYRIGHTS='\(\( \* Copyright (c) 20..\(-20..\|, 20..\)\? [^#]\+#x#\)\+\( \*#x# \* \(Stolen[^#]*\|Based on [^#]*\)#x#\)\?\)'
         _cat - |
         \
         sed '1s%^\(/\* SPDX-License-Identifier: LGPL-2.1-only \*/\|\)#x#/\*#x# \* [^#]*#x# \*#x# \*[	 ]\+This library is free software; you can redistribute it and/or#x# \*[	 ]\+modify it under the terms of the GNU Lesser General Public#x# \*[	 ]\+License as published by the Free Software Foundation version 2.1#x# \*[	 ]\+of the License.#x# \*#x#'"$COPYRIGHTS"' \*/'"$NEWLINES"'%/\* SPDX-License-Identifier: LGPL-2.1-only \*/#x#/*#x#\2 */#x##x#%' |
         \
         sed '1s%^/\*#x# \* [^#]*#x# \*#x# \*[	 ]\+This library is free software; you can redistribute it and/or#x# \*[	 ]\+modify it under the terms of the GNU Lesser General Public#x# \*[	 ]\+License as published by the Free Software Foundation version 2.1#x# \*[	 ]\+of the License.#x# \*/'"$NEWLINES"'%/\* SPDX-License-Identifier: LGPL-2.1-only \*/#x##x#%' |
         \
         sed '1s%^\(\)/\*#x# \* [^#]*#x# \*#x# \*[	 ]\+This library is free software; you can redistribute it and/or#x# \*[	 ]\+modify it under the terms of the GNU Lesser General Public#x# \*[	 ]\+License as published by the Free Software Foundation version 2.1#x# \*[	 ]\+of the License.#x# \*#x#'"$COPYRIGHTS"' \*/'"$NEWLINES"'%/\* SPDX-License-Identifier: LGPL-2.1-only \*/#x#/*#x#\2 */#x##x#%' |
         \
         sed '1s%^\(/\* SPDX-License-Identifier: LGPL-2.1-only \*/\|\)#x#/\*#x# \* [^#]*#x# \*#x# \*[	 ]\+This library is free software; you can redistribute it and/or#x# \*[	 ]\+modify it under the terms of the GNU General Public License as#x# \*[	 ]\+published by the Free Software Foundation version 2 of the License.#x# \*#x#'"$COPYRIGHTS"' \*/'"$NEWLINES"'%/\* SPDX-License-Identifier: GPL-2.0-only \*/#x#/*#x#\2 */#x##x#%'
    }

    FILES=( $(files_all) )

    for f in "${FILES[@]}"; do
       echo "processing \"$f\"..."
       in_file "$f" | join | adjust | unjoin | out_file "$f"
    done

1 files changed, 1 insertions, 7 deletions

diff --git a/lib/route/link/bonding.c b/lib/route/link/bonding.c
index 11b6d3d1..1d8f89b7 100644
--- a/lib/route/link/bonding.c
+++ b/lib/route/link/bonding.c
@@ -1,11 +1,5 @@
+/* SPDX-License-Identifier: LGPL-2.1-only */
 /*
- * lib/route/link/bonding.c	Bonding Link Module
- *
- *	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 version 2.1
- *	of the License.
- *
  * Copyright (c) 2011-2013 Thomas Graf <tgraf@suug.ch>
  */