sync: use io_u_log_error() for more detailed error messages

Signed-off-by: Jens Axboe <axboe@fb.com>
parse: make suggestions for unknown options

Signed-off-by: Jens Axboe <axboe@fb.com>
lib/rand: fix bug with non uint64_t aligned random buffer fill

Now that we honor the compression percentage, we can easily
get buffer fills that are not aligned to uint64_t. Make
sure that __fill_random_buf() handles this correctly.

Signed-off-by: Jens Axboe <axboe@fb.com>