- ext pipe test should build binar
- criu no longer accepts "extra" empty arguments
- adduser doesn't add more than one same user

All this came unnoticed due to error in tests failure detection
(36a13cbd test: don't ignore errors other other tests)
Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>