ocamlbuild should look for ocamlfind on the path not in the root directory

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@13237 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
-which option for ocamlbuild

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@13238 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02