[xen]: pass '-linkpkg -dontlink unix' to ocamlfind

When using later OCaml versions we don't emit a myocamlbuild,
so we can't rely on rules there.

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Revert "[xen] add a -dontlink unix flag"

This reverts commit 2c04389d03b04aa4b02e31a85e0d2198a3e9c2cc.
Revert "[xen] fix the output_obj to include linkpkg"

This reverts commit a7b5014e66c17089a69e3b93a8205577d5e77e34.
Merge pull request #18 from djs55/add-linkpkg

[xen]: pass '-linkpkg -dontlink unix' to ocamlfind
fix unix-direct by linking the unix package correctly (previously it was always dropped)
mark 0.9.6
Remove generated myocamlbuild.ml on mirari clean.
Generate code that uses the `Ipaddr.V4` interface instead of `Nettypes`.

This means that Mirari now needs Mirage 0.9.5 and Mirage-ent 0.9.4
Replace opam by mirari in the help message. Fix #21.
XL configuration file is now created during configuration phase.
Output tuntap backend only when direct is selected.
New Mirari

Mirari now defines a configuration type for each possible implementation of the module types defined in mirage-types. It then generates the right files to be able to compile the projet for the different backends.
Use oasis
Add some basic test (which are currently failing)
Update autogen files
Update test
Update the tests
Upate _oasis
Update autogen files
More improvements

* add a clean command
* generate a valid Makefile
* start the jobs after evaluating their arguments
* expose V1 which specialize signature from mirage-types/V1 using Lwt.t instead of an abstract io