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

src/libsyntax/ast.rs

@@ -505,13 +505,13 @@ pub enum token_tree {
     tt_tok(span, ::parse::token::Token),
     // a delimited sequence (the delimiters appear as the first
     // and last elements of the vector)
-    tt_delim(~[token_tree]),
+    tt_delim(@mut ~[token_tree]),
     // These only make sense for right-hand-sides of MBE macros:
 
     // a kleene-style repetition sequence with a span, a tt_forest,
     // an optional separator (?), and a boolean where true indicates
     // zero or more (*), and false indicates one or more (+).
-    tt_seq(span, ~[token_tree], Option<::parse::token::Token>, bool),
+    tt_seq(span, @mut ~[token_tree], Option<::parse::token::Token>, bool),
 
     // a syntactic variable that will be filled in by macro expansion.
     tt_nonterminal(span, ident)