[xen] Port Netif to use the `Macaddr` module from `ocaml-ipaddr`.
Unhook `mir-run` from the build, as Mirari replaces it.
bump to 0.9.5 and correct deps in META files
Add a simple regression runner that builds the entire combination
of supported libraries.  It needs to be edited to set the variables
at the top to the correct pins (which can be blank)
sync CHANGES
use github urls, and only build Xen on Linux
mir-rt: minor tweak in output
add a parallel version of mir-rt that currently fails
run mir-rt-parallel under switch correctly
add a variant of mir-rt to test the non-pinned versions of packages
xen: we must have at-most-one xenstore client

The domain has a single ring which must be shared amongst all
threads who want xenstore access. The sharing is done by the
xenstore client (Xs_client_lwt) which maintains all the necessary
tables mapping request ids to calling threads and serialising
access to the shared ring contents. We must make sure that only
one client is ever created.

In the recent refactoring all users of xenstore must get themselves
a handle by calling 'make ()'. Unfortunately every thread created
a fresh xenstore client. The fix is to cache the first client that
is created and return that to future callers.

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
[kfreebsd] Bring checksum code in sync with the OCaml bindings.
[kfreebsd] Implement virtual MAC address for Mirage instances.
[kfreebsd] Rework `Netif.listen` to be more cooperative with other `lwt` threads.