Allow actually setting the synthesis voice when then generic module is used

[Samuel Thibault]

Hello,

Didier Spaier, le mer. 10 oct. 2018 00:41:56 +0200, a ecrit:
> +char *module_setvoice(char *voicename)
> +{
> +     int i;
> +     for (i = 0; generic_voices_list[i] != NULL; i++) {
> +     if (strcasecmp(generic_voices[i].name, voicename) == 0)
> +             return voicename;
> +     }
> +     return NULL;
> +}

It seems odd to call this function module_setvoice since it does not
actually set anything, it just tests the presence in the list. Perhaps
rather call it module_existsvoice and make it return a gboolean?

Samuel