Fix module alias in signature error for OCaml 4.01.0
Fix module alias in signature error for OCaml 4.01.0

Drup/ocaml-cohttp,mor1/ocaml-cohttp,marklrh/ocaml-cohttp,inhabitedtype/ocaml-cohttp,dsheets/ocaml-cohttp,edwintorok/ocaml-cohttp,marklrh/ocaml-cohttp,dsheets/ocaml-cohttp,marklrh/ocaml-cohttp,Drup/ocaml-cohttp,mor1/ocaml-cohttp,Drup/ocaml-cohttp,inhabitedtype/ocaml-cohttp,dsheets/ocaml-cohttp,edwintorok/ocaml-cohttp,edwintorok/ocaml-cohttp,inhabitedtype/ocaml-cohttp,mor1/ocaml-cohttp