[Toybox] [landley/toybox] Add ln -r (#145)

[Rob Landley]

On 11/4/19 12:50 PM, enh wrote:
> On Mon, Nov 4, 2019 at 6:10 AM Andrew Ilijic <ilijic.andrew at gmail.com> wrote:
>
> i'm generally pro long-options because i think they're easier to
> remember. rob is generally anti; in particular he really doesn't like
> cases where there's a long option without any corresponding short
> option. (though i think that's a good idea for rarely-used options
> because there are only 2*26 short options -- and far fewer _good_ ones
> -- and again, rarely used options are the ones where the more
> memorable long names are more helpful.)

Both because unix history and because I implemented the lib/args.c
infrastructure so short options could be [grouped] and it drags the longopts in
via correspondence with short options. It supports "bare longopts" but doesn't
have all same the tools for them, because I dunno what that syntax would look
like in the NEWTOY() optstr.

> checking my AOSP notes, --no-symlinks and --relative-to are both used,
> but i don't currently know of any other long options AOSP needs.

Sounds good. Keep in mind we can always add more later, but you can't easily
_remove_ them without breaking compatibility with what you had before.

Rob