pan: fix potential overrun in tag_report

  char *cuts_info[5];
  ...
  while (tok_num < 5 &&
      (cuts_info[++tok_num] = strtok(NULL, "\t ")) != NULL) ;

While above can run for tok_num == 4, in which case:
  cuts_info[++tok_num] becomes cuts_info[5]
and that is outside of cuts_info array.

Signed-off-by: Jan Stancek <jstancek@redhat.com>
Signed-off-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>