*: shrink: use Vladimir's "o+" specifier instead of xatou(opt_param)

function                                             old     new   delta
getopt32                                            1370    1385     +15
sulogin_main                                         490     494      +4
realpath_main                                         84      86      +2
sleep_main                                            76      77      +1
mt_main                                              256     257      +1
printenv_main                                         75      74      -1
fdformat_main                                        546     545      -1
usleep_main                                           44      42      -2
setlogcons_main                                       77      75      -2
ed_main                                             2654    2649      -5
deallocvt_main                                        69      64      -5
addgroup_main                                        373     368      -5
mkfs_minix_main                                     2989    2982      -7
tail_main                                           1221    1213      -8
sv_main                                             1254    1241     -13
du_main                                              348     328     -20
tftp_main                                            325     302     -23
split_main                                           581     558     -23
nc_main                                             1000     977     -23
diff_main                                            891     868     -23
arping_main                                         1797    1770     -27
ls_main                                              893     847     -46
od_main                                             2797    2750     -47
readprofile_main                                    1944    1895     -49
tcpudpsvd_main                                      1973    1922     -51
udhcpc_main                                         2590    2513     -77
grep_main                                            824     722    -102
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 5/22 up/down: 23/-560)         Total: -537 bytes
   text    data     bss     dec     hex filename
 796973     658    7428  805059   c48c3 busybox_old
 796479     662    7420  804561   c46d1 busybox_unstripped

1 files changed, 3 insertions, 3 deletions

diff --git a/util-linux/mkfs_minix.c b/util-linux/mkfs_minix.c
index 3fbdc2020..60031a5c3 100644
--- a/util-linux/mkfs_minix.c
+++ b/util-linux/mkfs_minix.c
@@ -627,7 +627,7 @@ int mkfs_minix_main(int argc ATTRIBUTE_UNUSED, char **argv)
         unsigned opt;
         char *tmp;
         struct stat statbuf;
-        char *str_i, *str_n;
+        char *str_i;
         char *listfile = NULL;
 
         INIT_G();
@@ -643,13 +643,13 @@ int mkfs_minix_main(int argc ATTRIBUTE_UNUSED, char **argv)
                 bb_error_msg_and_die("bad inode size");
 #endif
 
-        opt = getopt32(argv, "ci:l:n:v", &str_i, &listfile, &str_n);
+        opt_complementary = "n+"; /* -n N */
+        opt = getopt32(argv, "ci:l:n:v", &str_i, &listfile, &G.namelen);
         argv += optind;
         //if (opt & 1) -c
         if (opt & 2) G.req_nr_inodes = xatoul(str_i); // -i
         //if (opt & 4) -l
         if (opt & 8) { // -n
-                G.namelen = xatoi_u(str_n);
                 if (G.namelen == 14) G.magic = MINIX1_SUPER_MAGIC;
                 else if (G.namelen == 30) G.magic = MINIX1_SUPER_MAGIC2;
                 else bb_show_usage();