[PATCH 11/19] RISC-V: avoid strdup()

[Jiawei]

> Along with xmalloc(), xstrdup() wants using.
>
> --- a/bfd/elfxx-riscv.c
> +++ b/bfd/elfxx-riscv.c
> @@ -2589,7 +2589,7 @@ riscv_copy_subset_list (riscv_subset_lis
>  {
>    riscv_subset_list_t *new = xmalloc (sizeof *new);
>    new->head = riscv_copy_subset (new, subset_list->head);
> -  new->arch_str = strdup (subset_list->arch_str);
> +  new->arch_str = xstrdup (subset_list->arch_str);
>    return new;
>  }
>
> --- a/gas/config/tc-riscv.c
> +++ b/gas/config/tc-riscv.c
> @@ -358,7 +358,7 @@ riscv_set_arch (const char *s)
>    riscv_release_subset_list (riscv_rps_as.subset_list);
>    riscv_parse_subset (&riscv_rps_as, s);
>    riscv_arch_str (xlen, riscv_rps_as.subset_list, true/* update */);
> -  file_arch_str = strdup (riscv_rps_as.subset_list->arch_str);
> +  file_arch_str = xstrdup (riscv_rps_as.subset_list->arch_str);
>
>    riscv_set_rvc (riscv_subset_supports (&riscv_rps_as, "c")
>           || riscv_subset_supports (&riscv_rps_as, "zca"));
> @@ -1435,7 +1435,7 @@ static bool
>  reglist_lookup (char **s, unsigned *reg_list)
>  {
>    *reg_list = 0;
> -  char *reglist = strdup (*s);
> +  char *reglist = xstrdup (*s);
>    if (reglist != NULL)
>      {
>        char *token = strtok (reglist, "}");
>
LGTM.

Reviewed-by: Jiawei <jiawei@iscas.ac.cn>