Fair eviction for i915, based on Daniel's drm_mm scanner

[Chris Wilson]

This is a resend of Daniel Vetter's drm mm work to provide a basis for
performing fair eviction in i915. I've taken the liberty of attaching the
acks and review comments from the previous round, so please look over and
check that they still hold true.

 drivers/gpu/drm/drm_mm.c                |  359 ++++++++++++++++++++-----------
 drivers/gpu/drm/i915/Makefile           |    1 +
 drivers/gpu/drm/i915/i915_drv.h         |   11 +-
 drivers/gpu/drm/i915/i915_gem.c         |  246 ++-------------------
 drivers/gpu/drm/i915/i915_gem_evict.c   |  242 +++++++++++++++++++++
 drivers/gpu/drm/i915/intel_ringbuffer.c |   46 +++--
 drivers/gpu/drm/i915/intel_ringbuffer.h |    1 -
 drivers/gpu/drm/ttm/ttm_bo.c            |    6 -
 drivers/gpu/drm/ttm/ttm_bo_util.c       |    2 -
 include/drm/drm_mm.h                    |   27 ++-
 10 files changed, 550 insertions(+), 391 deletions(-)
-ickle