Replace /usr/libexec/xenopsd with the more standard /usr/lib/xenopsd

We're not respecting the variables set in the configure script, instead
we're hardcoding paths in the vif script and udev rules.

Since /usr/lib/ is more standard than /usr/libexec/ this patches moves
everything to /usr/lib/

NB any .spec files referencing these scripts will need changing.

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
xc: ensure domain 0 xenstore entries exist on startup

xenops_server_xen maps uuids onto domids via the xenstore entries

  /vm/dom0-uuid/domains/0
  /vm/dom0-uuid/domains/0/create-time

If these don't exist then a 'driver domain' exception is thrown
when trying to create a device backend.

Note this is done before we daemonize and therefore we must throw
away the cached xenstore client, since it will be broken by the
fork().

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
configure: preprocess vif scripts and udev rules to substitute LIBEXEC(dir)

It turns out the flexibility is useful to accommodate both CentOS and Ubuntu
properly.

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Merge pull request #38 from djs55/xenserver-core-fixes

Partial resync with xenserver-core