Make client start if screen is 16bpp
Make client start if screen is 16bpp

The current glx code is looking for a rgb32 visual and always failing
if there is none. This means not even software rendering starts up
on e.g. 16bit visuals. This commit makes it pick software fallbacks
on 16bit visuals.

Long term we need to fix the gl implementation to do 16bpp too.

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