tests/warnings: fix reference file after adding header to the source file (commit 13923)

git-svn-id: http://caml.inria.fr/svn/ocaml/version/4.01@13924 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
PR#6046: testsuite picks up the wrong ocamlrun dlls

git-svn-id: http://caml.inria.fr/svn/ocaml/version/4.01@13925 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02