MINOR: session: rename private conns elements

By default, backend connections are attached to a server instance. This
allows to implement connection reuse. However, in some particular cases,
connection cannot be shared accross several clients. These connections
are considered and private and are attached to the session instance
instead.

These private connections are also indexed by the target server to not
mix them. All of this is implemented via a dedicated structure
previously named struct sess_srv_list.

Rename it to better reflect its usage to struct sess_priv_conns. Also
rename its internal members and all of the associated functions.

This commit is only a renaming, thus no functional impact is expected.

(cherry picked from commit 5ad801c0586bc07109860d40bb4e7da84c985cb0)
[cf: Must be backported because some fixes rely on it]
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 52373320a2564e1a56ecd47cb2e398bada85ea5d)
 [ad: pick for next commit apply. Context adjustment due to missing
  conn_backend_deinit() and srv_add_to_avail_list()]
Signed-off-by: Amaury Denoyelle <adenoyelle@haproxy.com>
9 files changed