Update syn to 0.12 and quote to 0.4

Author: Eijebong

Cargo.toml

@@ -30,8 +30,10 @@ serde = {version = "1.0", optional = true}
 smallvec = "0.6"
 
 [build-dependencies]
-syn = "0.11"
-quote = "0.3"
+syn = { version = "0.12", features = ["extra-traits", "fold"] }
+quote = "0.4.1"
+proc-macro2 = "0.2"
+
 [features]
 bench = []
 dummy_match_byte = []

build.rs

@@ -2,8 +2,11 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+#[macro_use]
 extern crate quote;
+#[macro_use]
 extern crate syn;
+extern crate proc_macro2;
 
 use std::env;
 use std::path::Path;