Fix output format warning for clang.

#include <cstring>

#include <functional>

#include <inttypes.h>

#include <iostream>

#include <string>

#include <vector>

#include "sequence_batch.h"

namespace chromap {

  void WriteMatrixOutputHead(uint64_t num_peaks, uint64_t num_barcodes,

                             uint64_t num_lines) {

    fprintf(matrix_output_file_, "%lu\t%lu\t%lu\n", num_peaks, num_barcodes,

    fprintf(matrix_output_file_, "%" PRIu64 "\t%" PRIu64 "\t%" PRIu64 "\n", num_peaks, num_barcodes,

            num_lines);

  }