[Toybox] Spent the evening on id.c.

[Rob Landley]

On the bright side, I think it's now fully standards compliant.  And
possibly slightly smaller.

The only remaining todo item on id.c is adding a test suite entry for
it, which requires container support.

Testing uid!=euid and gid!=egid means creating a suid wrapper, which is
generally a dangerous thing to leave lying around.  Properly testing the
command in general in an automated manner means creating temporary
uid/gid entries with known names, and creating processes that belong to
different users: again root access.

This can be done with either A) root access and chroot, B) a temporary
qemu system, C) an lxc-style container.  Of the three, I was vaguely
planning to add container support to toybox anyway...

But not today.

Georgi: sorry I didn't get further on your list.  Once I get hooked on
something I tend to want to get it _right_ before moving on.  I'll try
again in the morning.

Rob