[Mesa-dev] r600g: hyperz support

[j.glisse at gmail.com]

Ok so this time it should be it. Following patch seems to behave properly.
I am still in process of checking again that they don't regress anything,
i should be done monday or tuesday. If there is no objection by them i
will commit them.

Note that you need kernel patch for those and that by default hyperz get
enabled you can disable it by setting R600_HYPERZ=0 env variable.

On perf side quick benchmark shows improvement from 2% to 10% depending
on the benchmark and on the GPU.

Cheers,
Jerome