MINOR: listener: pause_listener() becomes suspend_listener()

We are simply renaming pause_listener() to suspend_listener() to prevent
confusion around listener pausing.

A suspended listener can be in two differents valid states:
 - LI_PAUSED: the listener is effectively paused, it will unpause on
   resume_listener()
 - LI_ASSIGNED (not bound): the listener does not support the LI_PAUSED
   state, so it was unbound to satisfy the suspend request, it will
   correcly re-bind on resume_listener()

Besides that, we add the LI_F_SUSPENDED flag to mark suspended listeners in
suspend_listener() and unmark them in resume_listener().

We're also adding li_suspend proxy variable to track the number of currently
suspended listeners:
That is, the number of listeners that were suspended through suspend_listener()
and that are either in LI_PAUSED or LI_ASSIGNED state.

Counter is increased on successful suspend in suspend_listener() and it is
decreased on successful resume in resume_listener()

--
Backport notes:

-> 2.4 only, as "MINOR: proxy/listener: support for additional PAUSED state"
was not backported:

Replace this:

    |                /* PROXY_LOCK is require
    |                proxy_cond_resume(px);

By this:

    |                ha_warning("Resumed %s %s.\n", proxy_cap_str(px->cap), px->id);
    |                send_log(px, LOG_WARNING, "Resumed %s %s.\n", proxy_cap_str(px->cap), px->id);

-> 2.6 and 2.7 only, as "MINOR: listener: make sure we don't pause/resume" was
custom patched:

Replace this:

    |@@ -253,6 +253,7 @@ struct listener {
    |
    | /* listener flags (16 bits) */
    | #define LI_F_FINALIZED           0x0001  /* listener made it to the READY||LIMITED||FULL state at least once, may be suspended/resumed safely */
    |+#define LI_F_SUSPENDED           0x0002  /* listener has been suspended using suspend_listener(), it is either is LI_PAUSED or LI_ASSIGNED state */
    |
    | /* Descriptor for a "bind" keyword. The ->parse() function returns 0 in case of
    |  * success, or a combination of ERR_* flags if an error is encountered. The

By this:

    |@@ -222,6 +222,7 @@ struct li_per_thread {
    |
    | #define LI_F_QUIC_LISTENER       0x00000001  /* listener uses proto quic */
    | #define LI_F_FINALIZED           0x00000002  /* listener made it to the READY||LIMITED||FULL state at least once, may be suspended/resumed safely */
    |+#define LI_F_SUSPENDED           0x00000004  /* listener has been suspended using suspend_listener(), it is either is LI_PAUSED or LI_ASSIGNED state */
    |
    | /* The listener will be directly referenced by the fdtab[] which holds its
    |  * socket. The listener provides the protocol-specific accept() function to

(cherry picked from commit d3ffba4512087a8d78cfb31416135ee4765bbb41)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 02bc60753bc78fb07f83eb11039b394989d90897)
Signed-off-by: Amaury Denoyelle <adenoyelle@haproxy.com>
(cherry picked from commit ec47da4ea469eeb96a4f61c42ae8fb505479876a)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit dc26d810e22920baa4d36e1962b18b340fc92003)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
diff --git a/src/protocol.c b/src/protocol.c
index 06a48c3..7e56b9a 100644
--- a/src/protocol.c
+++ b/src/protocol.c
@@ -162,10 +162,10 @@
 	HA_SPIN_UNLOCK(PROTO_LOCK, &proto_lock);
 }
 
-/* pauses all listeners of all registered protocols. This is typically
+/* suspends all listeners of all registered protocols. This is typically
  * used on SIG_TTOU to release all listening sockets for the time needed to
- * try to bind a new process. The listeners enter LI_PAUSED. It returns
- * ERR_NONE, with ERR_FATAL on failure.
+ * try to bind a new process. The listeners enter LI_PAUSED or LI_ASSIGNED.
+ * It returns ERR_NONE, with ERR_FATAL on failure.
  */
 int protocol_pause_all(void)
 {
@@ -177,7 +177,7 @@
 	HA_SPIN_LOCK(PROTO_LOCK, &proto_lock);
 	list_for_each_entry(proto, &protocols, list) {
 		list_for_each_entry(listener, &proto->receivers, rx.proto_list)
-			if (!pause_listener(listener, 0, 0))
+			if (!suspend_listener(listener, 0, 0))
 				err |= ERR_FATAL;
 	}
 	HA_SPIN_UNLOCK(PROTO_LOCK, &proto_lock);