nir/lower_io_to_temporaries: don't set compact on shadow vars

The compact flag doesn't make sense on local variables, since the
packing on them is up to the driver. This fixes nir_validate assertions
in some cases, particularly when lower_io_to_temporaries is used on
per-vertex inputs/outputs.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

src/compiler/nir/nir_lower_io_to_temporaries.c

@@ -141,6 +141,7 @@ create_shadow_temp(struct lower_io_state *state, nir_variable *var)
    temp->data.mode = nir_var_global;
    temp->data.read_only = false;
    temp->data.fb_fetch_output = false;
+   temp->data.compact = false;
 
    return nvar;
 }