spice: server: avoid video streaming of small images
spice: server: avoid video streaming of small images

I added a lower limit to the size of images that are being streamed.
The limit is only active in "filter" video streaming mode.
This will prevent blurry animated icons.

SPICE/spice,dezelin/spice,virtualAMP/spiceplay,alon/spice-server,mathslinux/spice,mathslinux/spice,fgouget/spice,dezelin/spice,freedesktop-unofficial-mirror/spice__spice,alon/spice-server,elmarco/spice,virtualAMP/spiceplay,SPICE/spice,freedesktop-unofficial-mirror/spice__spice,freedesktop-unofficial-mirror/spice__spice,Fantu/spice,elmarco/spice,freedesktop-unofficial-mirror/spice__spice,mathslinux/spice,dezelin/spice,elmarco/spice,virtualAMP/spiceplay,alon/spice-server,fgouget/spice,fgouget/spice,ya-mouse/spice,dezelin/spice,Fantu/spice,mathslinux/spice,Fantu/spice,alon/spice-server,fgouget/spice,ya-mouse/spice,dezelin/spice,elmarco/spice,Fantu/spice,elmarco/spice,freedesktop-unofficial-mirror/spice__spice,SPICE/spice,ya-mouse/spice,mathslinux/spice,alon/spice-server,virtualAMP/spiceplay