tree-wide: drop license boilerplate

Files which are installed as-is (any .service and other unit files, .conf
files, .policy files, etc), are left as is. My assumption is that SPDX
identifiers are not yet that well known, so it's better to retain the
extended header to avoid any doubt.

I also kept any copyright lines. We can probably remove them, but it'd nice to
obtain explicit acks from all involved authors before doing that.

tools/gdb-sd_dump_hashmaps.py

@@ -5,19 +5,6 @@
 #  This file is part of systemd.
 #
 #  Copyright 2014 Michal Schmidt
-#
-#  systemd 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 version 2.1 of the License, or
-#  (at your option) any later version.
-#
-#  systemd is distributed in the hope that it will be useful, but
-#  WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-#  Lesser General Public License for more details.
-#
-#  You should have received a copy of the GNU Lesser General Public License
-#  along with systemd; If not, see <http://www.gnu.org/licenses/>.
 
 import gdb
 

tools/make-directive-index.py

@@ -5,19 +5,6 @@
 #  This file is part of systemd.
 #
 #  Copyright 2012-2013 Zbigniew Jędrzejewski-Szmek
-#
-#  systemd 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 version 2.1 of the License, or
-#  (at your option) any later version.
-#
-#  systemd is distributed in the hope that it will be useful, but
-#  WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-#  Lesser General Public License for more details.
-#
-#  You should have received a copy of the GNU Lesser General Public License
-#  along with systemd; If not, see <http://www.gnu.org/licenses/>.
 
 import sys
 import collections

tools/make-man-index.py

@@ -6,19 +6,6 @@
 #
 #  Copyright 2012 Lennart Poettering
 #  Copyright 2013 Zbigniew Jędrzejewski-Szmek
-#
-#  systemd 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 version 2.1 of the License, or
-#  (at your option) any later version.
-#
-#  systemd is distributed in the hope that it will be useful, but
-#  WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-#  Lesser General Public License for more details.
-#
-#  You should have received a copy of the GNU Lesser General Public License
-#  along with systemd; If not, see <http://www.gnu.org/licenses/>.
 
 import collections
 import sys

tools/make-man-rules.py

@@ -5,19 +5,6 @@
 #  This file is part of systemd.
 #
 #  Copyright 2013, 2017 Zbigniew Jędrzejewski-Szmek
-#
-#  systemd 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 version 2.1 of the License, or
-#  (at your option) any later version.
-#
-#  systemd is distributed in the hope that it will be useful, but
-#  WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-#  Lesser General Public License for more details.
-#
-#  You should have received a copy of the GNU Lesser General Public License
-#  along with systemd; If not, see <http://www.gnu.org/licenses/>.
 
 from __future__ import print_function
 import collections

tools/oss-fuzz.sh

@@ -2,19 +2,6 @@
 # SPDX-License-Identifier: LGPL-2.1+
 #
 # Copyright 2017 Jonathan Rudenberg
-#
-# systemd 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 version 2.1 of the License, or
-# (at your option) any later version.
-#
-# systemd is distributed in the hope that it will be useful, but
-# WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-# Lesser General Public License for more details.
-#
-# You should have received a copy of the GNU Lesser General Public License
-# along with systemd; If not, see <http://www.gnu.org/licenses/>.
 
 set -ex
 

tools/xml_helper.py

@@ -5,19 +5,6 @@
 #  This file is part of systemd.
 #
 #  Copyright 2012-2013 Zbigniew Jędrzejewski-Szmek
-#
-#  systemd 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 version 2.1 of the License, or
-#  (at your option) any later version.
-#
-#  systemd is distributed in the hope that it will be useful, but
-#  WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-#  Lesser General Public License for more details.
-#
-#  You should have received a copy of the GNU Lesser General Public License
-#  along with systemd; If not, see <http://www.gnu.org/licenses/>.
 
 from lxml import etree as tree