[PATCH xserver 0/7] Server-side glvnd v2

[Adam Jackson]

This merges a change to context tag private data management that Kyle
had proposed. In general I'm quite happy with the cleanups this enables;
I have a few more in the pipeline that will require merging the glx
codegen scripts from Mesa to really accomplish, so I'd like to see this
initial roadblock out of the way.

This makes it possible to have different GLX providers on different
screens in Zaphod mode, and to switch between kernel/GLX driver stacks
without needing so much manual configuration.

- ajax