testsuite: Allow structural records in two tests that use pipes

src/test/bench/pingpong.rs

@@ -10,6 +10,10 @@
 
 // Compare bounded and unbounded protocol performance.
 
+#[allow(structural_records)]; // Pipes
+// Until a snapshot
+// xfail-pretty
+ 
 extern mod std;
 
 use pipes::{spawn_service, recv};

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

@@ -20,6 +20,8 @@
 
 // xfail-pretty
 
+#[allow(structural_records)]; // Pipes
+
 extern mod std;
 
 use core::option;