libsyntax: Remove some multi-gigabyte clones that were preventing bootstrapping on Windows.

src/libsyntax/ext/log_syntax.rs

@@ -25,7 +25,7 @@ pub fn expand_syntax_ext(cx: @ExtCtxt,
     cx.print_backtrace();
     io::stdout().write_line(
         print::pprust::tt_to_str(
-            &ast::tt_delim(tt.to_owned()),
+            &ast::tt_delim(@mut tt.to_owned()),
             get_ident_interner()));
 
     //trivial expression