add xenstore domain flag to hypervisor

add xenstore domain flag to hypervisor

In order to be able to have full support of a xenstore domain in Xen
add a "Xenstore-domain" flag to the hypervisor. This flag must be
specified at domain creation time and is returned by
XEN_DOMCTL_getdomaininfo.

It will allow the domain to retrieve domain information by issuing the
XEN_DOMCTL_getdomaininfo itself in order to be able to check for
domains having been destroyed. At the same time this flag will inhibit
the domain to be migrated, as this wouldn't be a very wise thing to do.

In case of a later support of a rebootable Dom0 this flag will allow to
recognize a xenstore domain already being present to connect to.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Reviewed-by: Andrew Cooper <andrew.cooper3@citirx.com>