message: librustzcash: Use "if let" syntax
diff: @@ -24,9 +24,8 @@ fn test_key_agreement() {
  let addr = loop {
  let mut d = [0; 11];
  rng.fill_bytes(&mut d);
  - match vk.to_payment_address(Diversifier(d), &params) {
  - Some(a) => break a,
  - None => {}
  + if let Some(a) = vk.to_payment_address(Diversifier(d), &params) {
  + break a;
  }
  };
  