[ransac] fixed core when n < nfit (return 0)
[ransac] fixed core when n < nfit (return 0)

carlodef/s2p,jmichel-otb/s2p,mnhrdt/s2p,jmichel-otb/s2p,MISS3D/s2p,MISS3D/s2p,dyoussef/s2p,mnhrdt/s2p,jmichel-otb/s2p,MISS3D/s2p,dyoussef/s2p,jmichel-otb/s2p,dyoussef/s2p,carlodef/s2p,MISS3D/s2p,dyoussef/s2p