SpiceDisplay: Fix rounding of mouse motion events with GTK-3.0
SpiceDisplay: Fix rounding of mouse motion events with GTK-3.0

Before this patch we were assuming that the GdkEventMotion value we receive
are always whole (integer) numbers, which is not the case with GTK-3.0.

Signed-off-by: Hans de Goede <9fa1be1a5b5729e4c6b404f34c9ce49ff4882fd8@redhat.com>

guodong/spice-gtk,mathslinux/spice-gtk,guodong/spice-gtk,flexVDI/spice-gtk,dezelin/spice-gtk,SPICE/spice-gtk,guodong/spice-gtk,Fantu/spice-gtk,elmarco/spice-gtk,SPICE/spice-gtk,dezelin/spice-gtk,fgouget/spice-gtk,freedesktop-unofficial-mirror/spice__spice-gtk,SPICE/spice-gtk,fgouget/spice-gtk,mathslinux/spice-gtk,flexVDI/spice-gtk,dezelin/spice-gtk,freedesktop-unofficial-mirror/spice__spice-gtk,guodong/spice-gtk,elmarco/spice-gtk,freedesktop-unofficial-mirror/spice__spice-gtk,fgouget/spice-gtk,dezelin/spice-gtk,Fantu/spice-gtk,elmarco/spice-gtk,mathslinux/spice-gtk,mathslinux/spice-gtk,Fantu/spice-gtk,Fantu/spice-gtk,SPICE/spice-gtk,elmarco/spice-gtk,freedesktop-unofficial-mirror/spice__spice-gtk