fsck_minix: getopt32-ification; code shrink; reduce stack usage;

fsck_minix: getopt32-ification; code shrink; reduce stack usage;
fix bug in map_block2: s/(blknr >= 256 * 256)/(blknr < 256 * 256)/

function                                             old     new   delta
get_inode_common                                       -     291    +291
add_zone_common                                        -     205    +205
ask                                                  229     215     -14
write_super_block                                    109      90     -19
write_block                                          653     629     -24
bad_zone                                              95      64     -31
read_block                                           241     198     -43
fsck_minix_main                                     3285    3195     -90
add_zone2                                            217      34    -183
add_zone                                             216      33    -183
recursive_check                                     1097     866    -231
recursive_check2                                    1340     956    -384
------------------------------------------------------------------------------
(add/remove: 2/0 grow/shrink: 0/10 up/down: 496/-1202)       Total: -706 bytes
   text    data     bss     dec     hex filename
 799349     661    7428  807438   c520e busybox_old
 798437     661    7428  806526   c4e7e busybox_unstripped