refactor: use designated initialization of array in luaX_tokens

[Melonges]

I suggest using RESERVED enum in luaX_tokens array like 
```
static const char *const luaX_tokens[] = { [TK_AND] = "and", [TK_BREAK] = "break", [TK_DO] = "do"};
```
this is a good approach that makes an explicit relationship between enum and array and makes it impossible to make a mistake here. 

The Linux kernel source has a lot of array literals like my example above.

[Francisco Olarte]

On Tue, 6 Aug 2024 at 17:43, Melonges <popov...@gmail.com> wrote:
> I suggest using RESERVED enum in luaX_tokens array like
> ```
> static const char *const luaX_tokens[] = { [TK_AND] = "and", [TK_BREAK] = "break", [TK_DO] = "do"};
> ```

If I am not too confused, this is C99, and lua is C89.

Francisco Olarte.