crocus/gen6: two fixes for sandybridge
One of these just fixes some REEMIT bugs.
The other just stops a CPU side infinite loop after a GPU hang with dEQP-GLES3.functional.transform_feedback.array.separate.lines.lowp_uvec4
This test can be made hang with 965 as well, but crocus seems a lot better at it. I think the geometry shader XFB is racy somewhere.