Make functional-update struct consts not an ICE

Author: jld

src/librustc/middle/check_const.rs

@@ -168,8 +168,8 @@ pub fn check_expr(sess: Session,
           expr_field(*) |
           expr_index(*) |
           expr_tup(*) |
-          expr_struct(*) |
-          expr_rec(*) => { }
+          expr_struct(_, _, None) |
+          expr_rec(_, None) => { }
           expr_addr_of(*) => {
                 sess.span_err(
                     e.span,