kvmclock: guest stop notification

kvmclock: guest stop notification

Often when a guest is stopped from the qemu console, it will report spurious
soft lockup warnings on resume.  There are kernel patches being discussed that
will give the host the ability to tell the guest that it is being stopped and
should ignore the soft lockup warning that generates.  This patch uses the qemu
Notifier system to tell the guest it is about to be stopped.

Signed-off-by: Eric B Munson <emunson@mgebm.net>
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>