Added code to not use gf-complete mult_by_one if region size is small (less than 16 bytes).
Added code to not use gf-complete mult_by_one if region size is small (less than 16 bytes).

leo-project/jerasure,cedricde/jerasure,cedricde/jerasure,windkit/jerasure,ceph/jerasure,tsuraan/Jerasure,tsuraan/Jerasure