message: Optionally write dependencies targets relative
  If dep-info-basedir is present in the config, write out dependency
  targets as relative to that directory.
diff: @@ -70,7 +70,15 @@ pub fn output_depinfo<'a, 'b>(context: &mut Context<'a, 'b>, unit: &Unit<'a>) ->
  let mut deps = HashSet::new();
  let mut visited = HashSet::new();
  let success = add_deps_for_unit(&mut deps, context, unit, &mut visited).is_ok();
  - let basedir = None; // TODO
  + let basedir_config = context.config.get_string("dep-info-basedir");
  + let basedir_config_ok = basedir_config.is_ok();
  + let basedir_val = basedir_config.unwrap_or(None).map(|s| s.val);
  + let basedir_string = basedir_val.unwrap_or("".to_string());
  + let basedir = if basedir_config_ok {
  + Some(basedir_string.as_str())
  + } else {
  + None
  + };
  for &(_, ref link_dst, _) in context.target_filenames(unit)?.iter() {
  if let Some(ref link_dst) = *link_dst {
  let output_path = link_dst.with_extension("d");
  