nir: Add a bool to int32 lowering pass

We also enable it in all of the NIR drivers.

Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Tested-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>

src/intel/compiler/brw_nir.c

@@ -822,6 +822,8 @@ brw_postprocess_nir(nir_shader *nir, const struct brw_compiler *compiler,
       nir_print_shader(nir, stderr);
    }
 
+   OPT(nir_lower_bool_to_int32);
+
    OPT(nir_convert_from_ssa, true);
 
    if (!is_scalar) {