message: prng: use merge_slices
diff: @@ -813,20 +813,14 @@ pub fn init_prng(cycle_data: &RightsContextData, constants: &RightsConstants, us
  let cycle_position: i32 = level_position(level.into(), blocks_per_cycle)?.try_into()?;
  // take the state (initially the random seed), zero bytes, the use string and the blocks position in the cycle as bytes, merge them together and hash the result
  - let mut rd = blake2b::digest_256(&merge_slices!(&state, &zero_bytes, use_string_bytes, &cycle_position.to_be_bytes())).to_vec();
  + let rd = blake2b::digest_256(&merge_slices!(&state, &zero_bytes, use_string_bytes, &cycle_position.to_be_bytes())).to_vec();
  // take the 4 highest bytes and xor them with the priority/slot (offset)
  let higher = num_from_slice!(rd, 0, i32) ^ offset;
  // set the 4 highest bytes to the result of the xor operation
  - //let sequence = blake2b::digest_256(&merge_slices!(&higher.to_be_bytes(), &rd[4..]));
  - let higher_b = higher.to_be_bytes();
  - rd[0] = higher_b[0];
  - rd[1] = higher_b[1];
  - rd[2] = higher_b[2];
  - rd[3] = higher_b[3];
  -
  - let sequence = blake2b::digest_256(&rd);
  + let sequence = blake2b::digest_256(&merge_slices!(&higher.to_be_bytes(), &rd[4..]));
  +
  Ok(sequence)
  }
  