opam - cmdliner - topkg cycle resolved upstream

[Hendrik Tews <hendrik@askra.de>]

Hi,

thanks to Daniel, the build dependency problems around opam,
cmdliner and topkg have now been resolved upstream:

- opam dropped the dependency on jsonm and, transitively, on
  uutf. Therefore, it should be possible to build opam without
  topkg. This is in the upstream master branch (PR Get rid of
  jsonm dep #3009) but has neither been merged into the 1.3
  branch nor been released.

- Just released cmdliner 1.0.1 contains a topkg free build and
  installation procedure with proper support for DESTDIR and
  bytecode only architectures.

- No changes in topkg. topkg can now be build after cmdliner and
  opam and rely on opam-installer.

I will move forward with updating the cmdliner package and then
packaging topkg for the first time.

Hendrik