i965: Support images with aux buffers

i965: Support images with aux buffers

Previously images did not support any auxiliary compression surfaces
(CCS, MCS, or HiZ).  That's about to change.  This patch just adds the
fields to __DRIimageRec to make auxiliary surfaces possible.

v2 (Jason Ekstrand):
 - Add an aux_pitch parameter as well as aux_offset

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Acked-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Topi Pohjolainen <topi.pohjolainen@intel.com>
Reviewed-by: Chad Versace <chadversary@chromium.org>