MINOR: quic: allocate a socket per quic-conn

MINOR: quic: allocate a socket per quic-conn

Allocate quic-conn owned socket if possible. This requires that this is
activated in haproxy configuration. Also, this is done only if local
address is known so it depends on the support of IP_PKTINFO.

For the moment this socket is not used. This causes QUIC support to be
broken as received datagram are not read. This commit will be completed
by a following patch to support recv operation on the newly allocated
socket.

This change is part of quic-conn owned socket implementation.
It may be backported to 2.7 after a period of observation.