[Nix-dev] Rolling back the free radeon driver.

[James Cook]

If you use the free radeon driver, please test / comment on
https://github.com/NixOS/nixpkgs/pull/175 .  I am rolling it back
because of https://github.com/NixOS/nixpkgs/issues/163 .  Actually, if
the newer version of the radeon driver was working for you, I'd be
curious to hear about it, because based on a discussion with #radeon,
I'd expect others to be having similar troubles to me unless they
disabled KMS.

To work properly, the newer radeon driver requires a newer version of
libdrm, which in turn requires a newer version of mesa.  I made a pull
request at https://github.com/NixOS/nixpkgs/pull/171 , but it was
pointed out that the newer version of mesa isn't a stable version, so
that's not going into master just yet.

James