SSL_CIPHER_find: heed new nightly clippy warning

[ctz]

warning: operator precedence can trip the unwary
    --> src/entry.rs:1473:18
     |
1473 |         let id = (slice[0] as u16) << 8 | (slice[1] as u16);
     |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider parenthesizing your expression: `((slice[0] as u16) << 8) | (slice[1] as u16)`
     |
     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#precedence
     = note: `#[warn(clippy::precedence)]` on by default