seize: Fix size error in creds_dumpable()

The goal of this function is to compare everything except caps,
but caps size is took to compare. It's wrong, there must be
used offsetof(struct proc_status_creds, cap_inh) instead.

Also, sigpnd may be different too.

v3: Move excluding sigpnd from comparation in this patch (was in another patch).
    Reorder fields in seize_task_status().

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>