librustc: Make the Drop trait use explicit self

src/libstd/future.rs

@@ -28,7 +28,7 @@ pub struct Future<A> {
 // FIXME(#2829) -- futures should not be copyable, because they close
 // over fn~'s that have pipes and so forth within!
 impl<A> Future<A> : Drop {
-    fn finalize() {}
+    fn finalize(&self) {}
 }
 
 priv enum FutureState<A> {