The Spice agent implements a simple serial mechanism to avoid clipboard
races between client & guest. See:
https://gitlab.freedesktop.org/spice/spice-protocol/-/commit/045a6978d6dbbf7046affc5c321fa8177c8cce56



Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>