testsuite: continue making it work without installing OCaml; also make it independent of the user's .ocamlinit

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@13687 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
testsuite/typing-warnings: update ref file with new warning introduced in r13683

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@13688 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02