message: Fix a build error in windows debug build
  Required by std::_Debug_range<_FwdIt> in std::lower_bound function.
diff: @@ -96,6 +96,10 @@ class IndicesRowIterator
  return (row_idx_ != other.row_idx_);
  }
  + bool operator<(const IndicesRowIterator& other) const {
  + return (row_idx_ < other.row_idx_);
  + }
  +
  bool operator==(const IndicesRowIterator& other) const {
  QCHECK_EQ(iter_, other.iter_);
  return (row_idx_ == other.row_idx_);
  