Thorin doesn't even emit closures correctly anymore

[Hugobros3]

Writing some tests to diagnose closure conversion without external functions, I modified the sample from: #177 and found the LLVM codegen fails to emit the function part (it declares it, but never defines it), leading to an invalid module. Whoops.

fn nop(_: i32) -> () {}

fn capture(a : i32) = @|body : fn(i32) -> ()| {
    body(a)
};

#[export]
fn c(i : i32) {
    let mut a = capture(i);

    fn inner_loop(n : i32) -> () {
        if (n <= 0) {
            a (nop);
        } else {
            inner_loop(n - 1);
        }
    }

    inner_loop(1);
}