Check for presence of robust futex list is in the reality
(futex_rla_len != 0).

That does code on dumping, in get_task_futex_robust_list():
> ret = syscall(SYS_get_robust_list, pid, &head, &len);
> if (ret < 0 && errno == ENOSYS) {
[..]
> 	len = 0;
[..]
> }
[..]
> info->futex_rla_len	= (u32)len;

And in images: futex_rla_len == 0 means that futex is not present.

So, we don't need additional restorer's parameter `has_futex'
which is always true, remove it.
Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>