spice: notify spice server on vm start/stop

spice: notify spice server on vm start/stop

Spice server needs to know about the vm state in order to prevent
attempts to write to devices when they are stopped, mainly during
the non-live stage of migration.
Instead, spice will take care of restoring this writes, on the migration
target side, after migration completes.

Signed-off-by: Yonit Halperin <yhalperi@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
(cherry picked from commit f5bb039c6d97ef3e664094eab3c9a4dc1824ed73)

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>