Add source code licenses

src/bindgen/annotation.rs

src/bindgen/cargo_expand.rs

src/bindgen/cargo_toml.rs

src/bindgen/cdecl.rs

src/bindgen/config.rs

src/bindgen/items.rs

src/bindgen/library.rs

src/bindgen/mod.rs

src/bindgen/rename.rs

src/bindgen/rust_lib.rs

src/bindgen/utilities.rs

src/bindgen/writer.rs

src/lib.rs

src/logging.rs

src/main.rs