The page server already knows how to create a TCP server and client. The
code has been hidden behind static-s in page-xfer.c. This commit moves
the common TCP server/client code to util.c to be able to also use it
in the upcoming remote lazy-server/lazy-client userfaultfd enhanced criu.
Signed-off-by: Adrian Reber <areber@redhat.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>