Hide internal details from the vchan interface
Hide internal details from the vchan interface

Signed-off-by: David Scott <63c9eb0ea83039690fefa11afe17873ba8278a56@eu.citrix.com>

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