gsettingsbackend: a minor simplification
Change the order of the arguments on the (internal) keys_changed callback in
GSettingsListenerVTable.
This means that all functions in the table now fit the following signature:
void (* f) (GObject *target,
GSettingsBackend *backend,
const gchar *name_or_path,
gpointer origin_tag,
const gchar * const *names);
allowing the possibility of arguments ignored at the end.
This allows us to simplify our dispatch-to-thread code in GSettingsBackend,
making it a bit less generic.
So far, this should be a straight refactor.
https://bugzilla.gnome.org/show_bug.cgi?id=710367