SSE2 SIMD: Fix prog Huffman enc. error if Sl%16==0 (regression introduced by 5b177b3cab5cfb661256c1e74df160158ec6c34e) The SSE2 implementation of progressive Huffman encoding performed extraneous iterations when the scan length was a multiple of 16. Based on: https://github.com/rouault/libjpeg-turbo/commit/bb7f1ef98305da915e581b59bd0ec2ef7bdb8468 Fixes #335 Closes #367