Fix a bug in the transpose code.

Change-Id: I1ce997329c7d59b831b84bf41d470ce686fea566

internal/ceres/compressed_row_sparse_matrix.cc

diff --git a/internal/ceres/compressed_row_sparse_matrix.cc b/internal/ceres/compressed_row_sparse_matrix.cc
index d0c10b2..b8e1a40 100644
--- a/internal/ceres/compressed_row_sparse_matrix.cc
+++ b/internal/ceres/compressed_row_sparse_matrix.cc
@@ -78,7 +78,7 @@
                                               int* transpose_cols,
                                               double* transpose_values) {
   // Explicitly zero out transpose_rows.
-  std::fill(transpose_rows, transpose_rows + num_nonzeros, 0.0);
+  std::fill(transpose_rows, transpose_rows + num_cols, 0);
 
   // Count the number of entries in each column of the original matrix
   // and assign to transpose_rows[col + 1].