Add a target to create an OPAM package.

git-svn-id: svn://svn.forge.ocamlcore.org/svn/tuareg/trunk@499 a37b5e43-4b7f-4128-9b7a-df1949a3dd69
Version 2.0.7

git-svn-id: svn://svn.forge.ocamlcore.org/svn/tuareg/trunk@500 a37b5e43-4b7f-4128-9b7a-df1949a3dd69
Do not regenerate tuareg-site-file.el if no source changed.

git-svn-id: svn://svn.forge.ocamlcore.org/svn/tuareg/trunk@502 a37b5e43-4b7f-4128-9b7a-df1949a3dd69