intel/nir: Re-run int64 lowering in postprocess_nir

We're about to start doing 64-bit pointer calculations in ANV.  They
will get applied after brw_preprocess_nir which is where we currently do
64-bit integer arithmetic lowering.  Because we're adding 64-bit integer
arithmetic after the initial lowering has happened, we need to lower
again.

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>

src/intel/compiler/brw_nir.c

@@ -854,6 +854,7 @@ brw_postprocess_nir(nir_shader *nir, const struct brw_compiler *compiler,
    UNUSED bool progress; /* Written by OPT */
 
    OPT(brw_nir_lower_mem_access_bit_sizes);
+   OPT(nir_lower_int64, nir->options->lower_int64_options);
 
    do {
       progress = false;