fix 16bpp support on cairo_canvas
fix 16bpp support on cairo_canvas

Signed-off-by: Izik Eidus <0f4d5ad8fceb71158793af13424905ac12569440@redhat.com>

SPICE/spice-common,fgouget/spice-common,freedesktop-unofficial-mirror/spice__spice-common,elmarco/spice-common,elmarco/spice-common,SPICE/spice-common,fgouget/spice-common,Fantu/spice-common,fgouget/spice-common,fgouget/spice-common,freedesktop-unofficial-mirror/spice__spice-common,Fantu/spice-common,Fantu/spice-common,elmarco/spice-common,freedesktop-unofficial-mirror/spice__spice-common,Fantu/spice-common,elmarco/spice-common,freedesktop-unofficial-mirror/spice__spice-common,SPICE/spice-common