Fix run-pass-fulldeps/qquote.rs

Author: brson

src/test/run-pass-fulldeps/qquote.rs

@@ -95,7 +95,7 @@ fn check_pp<T>(cx: fake_ext_ctxt,
     stdout().write_line(s);
     if expect != ~"" {
         error!("expect: '%s', got: '%s'", expect, s);
-        assert str == expect;
+        assert s == expect;
     }
 }