[Partial RFC] modesetting: support dri3 through glamor

This was really trivial, took me about an hour. I had some issues running Vulkan due to DRI3 issues(without MESA and using modesetting), that may have been because my distrubution didnt compile it for some reason though. This is only compile tested right now(on server 1.20), because I think there is something I missed here(as in DRI3 is supported in modesetting somewhere else I dont know about), hence the [Partial RFC].