Get arrays out of save_and_set and check_and_restore, as it is an
overkill to give to the function wich should work with only one
element of array the whole array.

These makes them reusable in future test of ipv6 config.
Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Reviewed-by: Andrew Vagin <avagin@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>