Update mod.rs

removes trailing whitespaces, replaces TODO with FIXME

src/libstd/thread/mod.rs

@@ -389,8 +389,8 @@ impl Builder {
     {
         unsafe { self.spawn_unchecked(f) }
     }
-    
-    /// TODO: Doc
+
+    /// FIXME: Doc
     #[unstable(feature = "thread_spawn_unchecked", issue = "0")]
     pub unsafe fn spawn_unchecked<'a, F, T>(self, f: F) -> io::Result<JoinHandle<T>> where
         F: FnOnce() -> T, F: Send + 'a, T: Send + 'a
@@ -425,7 +425,7 @@ impl Builder {
             native: Some(imp::Thread::new(stack_size, Box::new(main))?),
             thread: my_thread,
             packet: Packet(my_packet),
-        }))   
+        }))
     }
 }