Add hostname resolution in setup_tcp_client(). This change allows a
valid hostname to be provided as value for --address option when
connecting to page server.

This change is needed for the following path which removes
setup_TCP_client_socket() from img-proxy.c. In this function the
hostname resolution was implemented using gethostbyname()

However, here we use `getaddrinfo` instead because gethostbyname() is
marked obsolescent in POSIX.1-2001 and is removed in POSIX.1-2008
specifications.
Signed-off-by: Radostin Stoyanov <rstoyanov1@gmail.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>