Fix compilation of the unikernel example
Fix compilation of the unikernel example

djs55/ocaml-vchan,mirage/ocaml-vchan,djs55/ocaml-vchan,samoht/ocaml-vchan,samoht/ocaml-vchan,djs55/ocaml-vchan,mirage/ocaml-vchan,samoht/ocaml-vchan,mirage/ocaml-vchan