remove unnecessary heap allocation (#2628)

Author: thechampagne

bindgen/clang.rs

@@ -1820,7 +1820,7 @@ impl TranslationUnit {
         let fname = CString::new(file).unwrap();
         let _c_args: Vec<CString> = cmd_args
             .iter()
-            .map(|s| CString::new(s.clone().into_boxed_bytes()).unwrap())
+            .map(|s| CString::new(s.as_bytes()).unwrap())
             .collect();
         let c_args: Vec<*const c_char> =
             _c_args.iter().map(|s| s.as_ptr()).collect();