soccr: move connect from criu to soccr

We will need to disable the repair mode before connect()
to restore syn-sent sockets. And even now connect() looks
like a part of internal logic of libsoccr.

travis-ci: success for series starting with [01/21] build: install libnet-dev
v2: remove libsoccr_set_sk_data_unbound() from soccr.h
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>