Add SPDX license (but not copyright) headers to all files which follow a
certain pattern in their existing non-machine-readable header comment.
This commit was entirely generated using the command:
```
git ls-files gio/*.[ch] | xargs perl -0777 -pi -e 's/\n \*\n \* This library is free software; you can redistribute it and\/or\n \* modify it under the terms of the GNU Lesser General Public/\n \*\n \* SPDX-License-Identifier: LGPL-2.1-or-later\n \*\n \* This library is free software; you can redistribute it and\/or\n \* modify it under the terms of the GNU Lesser General Public/igs'
```
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Helps: #1415
There are no public 'exporter' objects, so don't allude to them
in the function names. At the same time, we want to make it clear
that these functions are D-Bus specific.
The new APIs are
g_action_group_dbus_export_start
g_action_group_dbus_export_query
g_action_group_dbus_export_stop
g_menu_model_dbus_export_start
g_menu_model_dbus_export_query
g_menu_model_dbus_export_stop
