It's rare to have a final alu clause on normal shaders (exports)
but tess shaders write to LDS as their output, so we see some
alu clauses, and the CF_END get put in the wrong place.
This makes sure to update last_cf correctly.
Acked-By: Roland Scheidegger <sroland@vmware.com> Signed-off-by: Dave Airlie <airlied@redhat.com>