Listing ch03-19 should use output

[NejcZdovc]

https://github.com/rust-lang/book/blob/master/src/ch03-03-how-functions-work.md has hardcoded output. It also has a TODO in it

<!--TODO: not extracting this because the new error message is incorrect; see
https://github.com/rust-lang/rust/issues/65254 -->

rust-lang/rust#65254 was fixed so error message is correct again.