Rename librustsyntax to libsyntax

Per issue #2418.

src/libsyntax/ext/log_syntax.rs

@@ -0,0 +1,15 @@
+import base::*;
+import io::writer_util;
+
+fn expand_syntax_ext(cx: ext_ctxt, sp: codemap::span, arg: ast::mac_arg,
+                     _body: ast::mac_body) -> @ast::expr {
+    let args = get_mac_args_no_max(cx,sp,arg,0u,"log_syntax");
+    cx.print_backtrace();
+    io::stdout().write_line(
+        str::connect(vec::map(args,
+                              {|&&ex| print::pprust::expr_to_str(ex)}), ", ")
+    );
+
+    //trivial expression
+    ret @{id: cx.next_id(), node: ast::expr_rec([], option::none), span: sp};
+}