[Toybox] Slight delay in the release until I add tr.c.

[Rob Landley]

I tried to build busybox 1.21.1 with aboriginal linux and it barfed
because the libm linking test uses tr in a way that busybox's tr
implementation doesn't support.

Sigh.

So I have to write a tr that can actually work to build busybox, and
stick it in toybox. (Ok, I _could_ patch it out of busybox, but it's on
the todo list anyway...)

Rob