lwip 0.3.15

#![allow(non_upper_case_globals)]
#![allow(non_camel_case_types)]
#![allow(non_snake_case)]
#![allow(improper_ctypes)]
#![allow(dead_code)]
#![allow(clippy::all)]

// Note the bindings are generated on macOS.
// This shouldn't be problematic since we only use lwip functions from
// the bindings. We should have the bindings automatically generated
// for each target at compile time, but I couldn't find a way to make
// bindgen work with cross.
include!(concat!(env!("OUT_DIR"), "/bindings.rs"));