To add OASIS Xen "support", you need to:

- Add the clump of code at the end of myocamlbuild.ml to your project's
  myocamlbuild. This will not be overwritten when you regenerate the
  myocamlbuild if you put it after the OASIS_STOP marker.

- Run s/native/.m.o,native/g on _tags after you regenerate it to add the
  Xen output_obj target to it.
