Always pass --no-unstable-rust per rust-bindgen.py

Author: jdub

libbindgen/tests/tests.rs

@@ -86,6 +86,7 @@ fn spawn_bindgen(header: &PathBuf, builder: libbindgen::Builder) -> Result<(), (
 fn create_bindgen_builder(header: &PathBuf) -> libbindgen::Builder {
     let mut builder = libbindgen::builder()
         .header(header.to_str().unwrap())
+        .no_unstable_rust()
         .raw_line("")
         .raw_line("#![allow(non_snake_case)]")
         .raw_line("");