Remove trailing whitespace.

Author: nikomatsakis

src/test/run-pass/issue-3168.rs

@@ -18,13 +18,13 @@ pub fn main() {
             p2.recv();
             error!("sibling fails");
             fail!();
-        }   
+        }
         let (p3,c3) = comm::stream();
         c.send(c3);
         c2.send(());
         error!("child blocks");
         p3.recv();
-    };  
+    };
     error!("parent tries");
     assert !p.recv().try_send(());
     error!("all done!");