Do not track unused type declarations created by 'include'.

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@14158 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
A tiny tool which use the new -keep-locs to find unused exported values in a project.

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@14159 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02