Include benchmarks in pretty-print tests

src/test/bench/shootout-binarytrees.rs

@@ -1,3 +1,4 @@
+// xfail-pretty
 
 use std;
 import std::int;

src/test/bench/shootout-fannkuchredux.rs

@@ -1,4 +1,4 @@
-
+// xfail-pretty
 
 // Based on Isaac Gouy's fannkuchredux.csharp
 use std;

src/test/bench/shootout-fibo.rs

@@ -1,4 +1,4 @@
-
+// xfail-pretty
 
 
 // -*- rust -*-

src/test/bench/shootout-nbody.rs

@@ -1,3 +1,4 @@
+// xfail-pretty
 // based on:
 // http://shootout.alioth.debian.org/u32/benchmark.php?test=nbody&lang=java
 

src/test/bench/shootout-pfib.rs

@@ -1,3 +1,4 @@
+// xfail-pretty
 // -*- rust -*-
 
 /*

src/test/bench/task-perf-word-count.rs

@@ -1,3 +1,4 @@
+// xfail-pretty
 /**
    A parallel word-frequency counting program.