nir/linking: fix issue with two compact variables in a row. (v2)

nir/linking: fix issue with two compact variables in a row. (v2)

If we have a clip dist float[1] compact followed by a tess factor
float[2] we don't want to overlap them, but the partial check
only happens for non-compact vars.

This fixes some issues seen with my sw vulkan layer with
dEQP-VK.clipping.user_defined.clip_distance*

v2: v1 failed with clip/cull mixtures, since in that
case the cull has a location_frac to follow after the clip
so only reset if we get a location_frac of 0 in a subsequent
clip var

Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4635>