nir/opt_vectorize_io: fix skipped output vectorization if inputs were vectorized

Fixes: 2514999c9c - nir: add nir_opt_vectorize_io, vectorizing lowered IO

Reviewed-by: Georg Lehmann <dadschoorse@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31454>

src/compiler/nir/nir_opt_vectorize_io.c

@@ -465,8 +465,9 @@ nir_opt_vectorize_io(nir_shader *shader, nir_variable_mode modes)
        * but that is only done when outputs are ignored, so vectorize them
        * separately.
        */
-      return nir_opt_vectorize_io(shader, nir_var_shader_in) ||
-             nir_opt_vectorize_io(shader, nir_var_shader_out);
+      bool progress_in = nir_opt_vectorize_io(shader, nir_var_shader_in);
+      bool progress_out = nir_opt_vectorize_io(shader, nir_var_shader_out);
+      return progress_in || progress_out;
    }
 
    /* Initialize dynamic arrays. */