Refactor argument parser using cmdopt

[mohanson]

Modified part of the source code of cmdopt, the diff results are as follows

2,5d1
<  * Copied from https://bellard.org/nncp/nncp-2023-10-21.tar.gz
<  */
< 
< /*
7c3
<  *
---
>  * 
29d24
< #include "my_stdlib.h"
31d25
< #include "my_stdio.h"
34,35c28,30
< #include "my_string.h"
< #include "my_assert.h"
---
> #include <assert.h>
> #include "cutils.h"
> 
57c52
< 
---
>     
71c66
< 
---
>     
110,111d104
< /* See the reason: https://reviews.llvm.org/D103009 */
< #pragma clang optimize off
121d113
< #pragma clang optimize on
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<     arg_pos = 0;
<     for(optind = 0; optind < argc; ) {
---
>     arg_pos = 1;
>     for(optind = 1; optind < argc; ) {
217c209
< #endif
---
> #endif    
225c217
<     size_t len;
---
>     size_t len, i;
227c219
< 
---
>     
230d221
<         char l[256] = {0};
240c231
<                 strcat(l, " ");
---
>                 putchar(' ');
243c234
<             strcat(l, "-");
---
>             putchar('-');
245c236
<                 strcat(l, "-");
---
>                 putchar('-');
248c239,240
<             memcpy(&l[col+1], p, len);
---
>             for(i = 0; i < len; i++)
>                 putchar(p[i]);
250c242
< 
---
>             
255c247
< 
---
>         
257,264c249,252
<             if (d->arg_desc) {
<                 strcat(l, " ");
<                 strcat(l, d->arg_desc);
<                 col += 1 + strlen(d->arg_desc);
<             } else {
<                 strcat(l, " arg");
<                 col += 4;
<             }
---
>             if (d->arg_desc)
>                 col += printf(" %s", d->arg_desc);
>             else
>                 col += printf(" arg");
272c260
<             strcat(l, " ");
---
>             putchar(' ');
275,276c263
<         strcat(l, d->desc);
<         printf("%s", l);
---
>         printf("%s\n", d->desc);
302c289
< 
---
>     
332c319
< 
---
>     
348c335
< 
---
>