Print empty line between the two examples

rust/coffi/src/main.rs

fn main() {
    let x = unsafe { cos(3.1415) };
    println!("cos(3.1415) = {}", x);
    println!("");
    let mut img = png_image::new();
    let file_name = std::env::args().nth(1).unwrap_or(String::from("mei.png"));