Declare that js_of_ocaml is not compatible with compiler version 4.01.0

See the js_of_ocaml [issue](https://github.com/ocsigen/js_of_ocaml/issues/37?source=cc)
Merge pull request #1331 from pveber/patch-2

Declare that js_of_ocaml is not compatible with compiler version 4.01.0