Re: [PATCH v4 23/28] trailer: add new helper functions to API

>
> From: Linus Arver <linusa@google.com>
>
> This is a preparatory refactor for deprecating "new_trailer_item" from
> the API (which will let us deprecate
> parse_trailers_from_command_line_args()).
>
> Expose new helper functions from the API, because we'll be calling them
> from interpret-trailers.c soon when we move
> parse_trailers_from_command_line_args() there.
>
> Move free_new_trailers() from the builtin to trailer.c because later on
> we will adjust it to free arg_item structs, which are private to
> trailer.c.