completion: Add missing copyright and licensing headers

The copyright entries come from looking at `git log gio/completion/*`
and, in particular, `git log -- gio/gsettings-bash-completion.sh` (etc.)
as the files were moved after being originally written, and haven’t
really changed since.

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

Helps: #1415

gio/completion/gapplication

@@ -1,3 +1,20 @@
+#
+# Copyright 2013 Allison Karlitskaya
+#
+# 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 version 2.1 of the
+# licence, or (at your option) any later version.
+#
+# This 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 this library; if not, see <http://www.gnu.org/licenses/>.
+#
+# SPDX-License-Identifier: LGPL-2.1-or-later
 
 # shellcheck shell=bash
 

gio/completion/gdbus

@@ -1,3 +1,20 @@
+#
+# Copyright 2010 Red Hat, Inc.
+#
+# 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 version 2.1 of the
+# licence, or (at your option) any later version.
+#
+# This 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 this library; if not, see <http://www.gnu.org/licenses/>.
+#
+# SPDX-License-Identifier: LGPL-2.1-or-later
 
 # shellcheck shell=bash
 

gio/completion/gio

@@ -14,6 +14,7 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with this library; if not, see <http://www.gnu.org/licenses/>.
 #
+# SPDX-License-Identifier: LGPL-2.1-or-later
 
 # shellcheck shell=bash
 

gio/completion/gresource

@@ -1,3 +1,20 @@
+#
+# Copyright 2012 Red Hat, Inc.
+#
+# 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 version 2.1 of the
+# licence, or (at your option) any later version.
+#
+# This 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 this library; if not, see <http://www.gnu.org/licenses/>.
+#
+# SPDX-License-Identifier: LGPL-2.1-or-later
 
 # shellcheck shell=bash
 

gio/completion/gsettings

@@ -1,3 +1,22 @@
+#
+# Copyright 2010, 2012 Red Hat, Inc.
+# Copyright 2010 Allison Karlitskaya
+# Copyright 2011 Giovanni Campagna
+#
+# 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 version 2.1 of the
+# licence, or (at your option) any later version.
+#
+# This 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 this library; if not, see <http://www.gnu.org/licenses/>.
+#
+# SPDX-License-Identifier: LGPL-2.1-or-later
 
 # shellcheck shell=bash