Shrink Rust wasm size

lib.rs

#![feature(core_intrinsics, lang_items)]
#![no_main]
#![no_std]

#[lang = "panic_fmt"]
extern "C" fn panic_fmt(_args: ::core::fmt::Arguments, _file: &'static str, _line: u32) -> ! {
  use core::intrinsics;
  unsafe {
    intrinsics::abort();
  }
}

#[no_mangle]
pub extern "C" fn one() -> i32 {
  return None.unwrap();
}

// Compiled to wasm size shrink from 34 Kb to ~350b