rem: sprintf (buf, "Unknown error %d", errnum);
add: sprintf (buf, _("Unknown error %d"), errnum);
context: wstrerror(int errnum){#if defined(HAVE_STRERROR)    return strerror(errnum);#elif !defined(HAVE_STRERROR) && defined(BSD)    extern int errno, sys_nerr;#  ifndef __DECC    extern char *sys_errlist[];#  endif    static char buf[] = "Unknown error 12345678901234567890";    if (errno < sys_nerr)        return sys_errlist[errnum];    sprintf (buf, "Unknown error %d", errnum);    return buf;#else /* no strerror() and no sys_errlist[] */    static char buf[] = "Error 12345678901234567890";    sprintf(buf, "Error %d", errnum);    return buf;#endif}