Fix bug in DenseSparseMatrix::ToDenseMatrix().
Fix bug in DenseSparseMatrix::ToDenseMatrix().

Change-Id: I74a1a03149d74fbc4268ec3ce9d20e09746a7227

entylop/ceres-solver,stonier/ceres_solver,stonier/ceres_solver,timfel/ceres-bin,ysonggit/ceres-solver,DougFirErickson/ceres-solver,whuaegeanse/ceres-solver,jmwalls/ceres-solver-fork,entylop/ceres-solver,kartikkumar/ceres-solver,entylop/ceres-solver,ikoruk/ceres-solver,whuaegeanse/ceres-solver,kartikkumar/ceres-solver,kartikkumar/ceres-solver,stonier/ceres_solver,timfel/ceres-bin,timfel/ceres-bin,jmwalls/ceres-solver-fork,whuaegeanse/ceres-solver,timfel/ceres-bin,ysonggit/ceres-solver,DougFirErickson/ceres-solver,stonier/ceres_solver,ikoruk/ceres-solver,entylop/ceres-solver,kartikkumar/ceres-solver,DougFirErickson/ceres-solver,jmwalls/ceres-solver-fork,ikoruk/ceres-solver,whuaegeanse/ceres-solver,ikoruk/ceres-solver,ysonggit/ceres-solver,DougFirErickson/ceres-solver,ikoruk/ceres-solver,ysonggit/ceres-solver,jmwalls/ceres-solver-fork