This commit adds initial support for acceleration
on SI chips.  egltri is starting to work.

The SI/R600 llvm backend is currently included in mesa
but that may change in the future.

The plan is to write a single gallium driver and
use gallium to support X acceleration.

This commit contains patches from:
Tom Stellard <thomas.stellard@amd.com>
Michel Dänzer <michel.daenzer@amd.com>
Alex Deucher <alexander.deucher@amd.com>
Vadim Girlin <vadimgirlin@gmail.com>

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

The following commits were squashed in:

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radeonsi: Remove unused winsys pointer

This was removed from r600g in commit:

commit 96d88293
Author: Marek Olšák <maraeo@gmail.com>
Date:   Fri Feb 17 01:49:49 2012 +0100

    gallium: remove unused winsys pointers in pipe_screen and pipe_context

    A winsys is already a private object of a driver.

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