Always scramble buffers, if scramble_buffers is set

This makes scramble_buffers and zero_buffers cooperate nicely.

Signed-off-by: Jens Axboe <axboe@fb.com>
Use fio_option_is_set() for ioprio setting

Signed-off-by: Jens Axboe <axboe@fb.com>
Fix server/client set_options conversion

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