conf-emacs dep missing in editors/emacs/dune-project

[fblanqui]

after dune clean, dune build fails:

File "editors/emacs/dune", line 5, characters 7-19:
5 |   (run %{bin:emacs} --batch --quick --funcall batch-byte-compile
           ^^^^^^^^^^^^
Error: Program emacs not found in the tree or in PATH
 (context: default)

[ejgallego]

Actually the dep there won't be enough, you still need to run opam for the deps to update.

[gabrielhdt]

This is kind of fixed by #1090 because the dune related install is abandoned.