Update to ocaml-xen-lowlevel-libs.0.9.16, with support for xen-4.2 and 4.4

Signed-off-by: David Scott <dave.scott@citrix.com>
xenopsd: build and use xenguest from ocaml-xen-lowlevel-libs

Signed-off-by: David Scott <dave.scott@citrix.com>
xenopsd: remove --disable-xenguestbin from configure

This relies on the configure script automatically disabling
xenguest.

Signed-off-by: David Scott <dave.scott@citrix.com>
ocaml-xen-lowlevel-libs.0.9.17

Signed-off-by: David Scott <dave.scott@citrix.com>
Update ocaml-xen-lowlevel-libs.0.9.18

Signed-off-by: David Scott <dave.scott@citrix.com>
Merge pull request #468 from djs55/trusty-updates

Package updates needed for trusty