Function rustdoc::html::format::generate_macro_def_id_path

fn generate_macro_def_id_path(
    def_id: DefId,
    cx: &Context<'_>,
    root_path: Option<&str>
) -> Result<(String, ItemType, Vec<Symbol>), HrefError>

This function is to get the external macro path because they are not in the cache used in href_with_root_path.