fio-genzipf results output are slightly wrong, it doesn't help to understand how...

fio-genzipf results output are slightly wrong, it doesn't help to understand how to use it:
 * The last row was not displayed
 * some useless variables were used
 * the calculation for the output table missed a few events, so the sum of 'No Hits' column was wrong
 * Wrong sample in genzipf.c header, used old style arguments
 * the help message for -o options was misleading.
 * useless define of DEF_NR.
 * default of default row number to a more common value of 20,
   instead of 23.