parser: Remove unnecessary back and forth during bitflags parsing.

src/bindgen/bitflags.rs

@@ -132,7 +132,7 @@ impl Flags {
     }
 }
 
-pub fn parse(tokens: &str) -> ParseResult<Bitflags> {
+pub fn parse(tokens: TokenStream) -> ParseResult<Bitflags> {
     let parser = Bitflags::parse;
-    parser.parse_str(tokens)
+    parser.parse2(tokens)
 }

src/bindgen/parser.rs

@@ -890,8 +890,7 @@ impl Parse {
             return;
         }
 
-        let tokens = item.mac.tts.to_string();
-        let bitflags = match bitflags::parse(&tokens) {
+        let bitflags = match bitflags::parse(item.mac.tts.clone()) {
             Ok(b) => b,
             Err(e) => {
                 warn!("Failed to parse bitflags invocation: {:?}", e);