[rust-lang/rust] Tweak irrefutable let else warning output

### ROOT CAUSE The `else` clause in the `let` statement is unreachable because the left-hand side (`Some(name)`) always matches, making the `else` block dead code. ### CODE FIX To fix the warning, remove the `else` clause since it's unreachable. The corrected code will directly assign `name_str` as `Some(name)`. ```rust pub fn say_hello(name: Option) { let name_str = Some(name); // TODO: greet the user by name. } ``` This removes the unreachable `else` block and simplifies the code.