egl,glx: Retire DRI2-the-X11-protocol
Nobody should be using the DRI2 X11 protocol these days, and we aren't testing this code. Retire it, since we don't have any plans to test and support it, nor any particular justification for the path to keep existing other than old xserver installations.
This leaves tons of infrastructure in place called "dri2", which is still a horribly overloaded name.
Edited by Emma Anholt