Fix OPT_FRAGMENT option first sequence number & length decoding.
Fix OPT_FRAGMENT option first sequence number & length decoding.


jdelgadoalfonso/openpgm,jdelgadoalfonso/openpgm,jdelgadoalfonso/openpgm,jdelgadoalfonso/openpgm,jdelgadoalfonso/openpgm,jdelgadoalfonso/openpgm