fix dependencies for ocaml < 4.02 (windows)
fix dependencies for ocaml < 4.02 (windows)

whitequark/ocaml-ctypes,whitequark/ocaml-ctypes,dsheets/ocaml-ctypes,dsheets/ocaml-ctypes,yallop/ocaml-ctypes,sjfloat/ocaml-ctypes,dsheets/ocaml-ctypes,whitequark/ocaml-ctypes,ocamllabs/ocaml-ctypes,ocamllabs/ocaml-ctypes,sjfloat/ocaml-ctypes,yallop/ocaml-ctypes,sjfloat/ocaml-ctypes