Remove libdebug and update tests.

src/test/run-pass/tuple-struct-construct.rs

@@ -8,11 +8,10 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-extern crate debug;
-
+#[deriving(Show)]
 struct Foo(int, int);
 
 pub fn main() {
     let x = Foo(1, 2);
-    println!("{:?}", x);
+    println!("{}", x);
 }