i965: Enable ARB_draw_indirect (and ARB_multi_draw_indirect) on Gen7+

.. and mark them off on the extensions list as done.

V2: Enable only if pipelined register writes work.
V3: Also update relnotes

Signed-off-by: Chris Forbes <chrisf@ijw.co.nz>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>

docs/relnotes/10.1.html

@@ -44,6 +44,7 @@ Note: some of the new features are only available with certain drivers.
 </p>
 
 <ul>
+<li>GL_ARB_draw_indirect on i965.</li>
 </ul>