[Toybox] which packages toybox replaces

[Rob Landley]

In https://github.com/landley/toybox/issues/168#issuecomment-583725500 firasuke
raised the issue of distros wanting to add "alternatives" annotations to their
toybox package, to say which other packages it replaces (or at least conflicts
with).

I gave him a dpkg-query loop that shows what packages debian commands were
installed from, but it might also be useful to go through Linux From Scratch and
check their "what packages each package installs" lists to see how that might
apply to toybox?

I started going through the first few packages from chapter 6 of
http://www.linuxfromscratch.org/lfs/downloads/9.0/LFS-BOOK-9.0-NOCHUNKS.html
(the square brackets mean not yet implemented but probably should):

file: file
m4: [m4]
bc: bc [dc]
binutils: [ar] [nm] [readelf] [size] strings (most other commands belong in qcc)
shadow: [chfn] [chpasswd] [chsh] [groupadd] [groupdel] [groupmod] [login]

Except with shadow we're _not_ doing chage, expiry, faillog, or lastlog, but an
argument could be made for all of those. Less so for logind, grpck... We're not
doing grpconv or grpunconv, and I don't see any argument EVER being made for
chgpasswd or groupmems (did you know group passwords were a thing?)

Ahem. This turns out to be nontrivial analysis. :P

Rob