test-kdbus: check for EOPNOTSUPP instead of ENOTSUPP

Signed-off-by: John de la Garza <john@jjdev.com>
Don't use nonexistent member of kdbus_pool_slice

Signed-off-by: Maciej Wereski <m.wereski@partner.samsung.com>
TODO: update
Merge remote-tracking branch 'kdbus/master' into 3.13/kdbus