glsl_to_tgsi: make sure copied instructions don't lose texture target. (v2)

glsl_to_tgsi: make sure copied instructions don't lose texture target. (v2)

The piglit draw-pixel-with-texture was asserting in the glsl->tgsi code,
due to 0 texture target, this makes sure the texture target is copied over
correctly when we copy instructions around.

v2: drive-by fix bitmap on the way past.

This avoids the assertion, have to contemplate fixing things as per the spec
later.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Brian Paul <brianp@vmware.com>