deletion proposal: unison 2.32 and 2.40

[Greg Troxel <gdt%lexort.com@localhost>]

(Unison suffers from having a new network protocol with every non-micro
release, so we have multiple versions.  In addition to interoperating
with other pkgsrc installations, there is the issue of interoperating
with Other Packaging Systems.)

Right now, 2.48 is pretty normal, but old, and 2.51 is arguably the
standard approach.

2.32 seems to be truly ancient.

2.40 is included in Ubuntu 1404, and I am aware of one person (not a
pkgsrc) user who wants to use 2.40 because they don't want to upgrade
their system (because it's too hard/dangerous, I think).  I don't mean
that as a reason we should keep it, just to put in perspective the kind
of oldness we are talking about.

In additinon, 2.32 and 2.40 do not build with the version of ocaml in
pkgsrc.   So anybody that wants them has to mess with old ocaml.

So, I hypothesize that zero people are using 2.32 and 2.40 from current
pkgsrc, and that therefore we should delete them.