intel/nir: Run copy-prop and DCE after lower_bool_to_int32

No shader-db impact on ICL with iris.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4338>

src/intel/compiler/brw_nir.c

@@ -927,6 +927,8 @@ brw_postprocess_nir(nir_shader *nir, const struct brw_compiler *compiler,
    OPT(nir_opt_move, nir_move_comparisons);
 
    OPT(nir_lower_bool_to_int32);
+   OPT(nir_copy_prop);
+   OPT(nir_opt_dce);
 
    OPT(nir_lower_locals_to_regs);