tests: Add note about packet_sock

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
sockets: Convert timestamps

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
tests: Update tcpbuf tests

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>