BUG/MEDIUM: peers: Be sure to always refresh recconnect timer in sync task

A sync task used to manage reconnect, sessions creation or shutdown and data
synchronization is responsible to refresh reconnect and heartbeat timers for
each remote peers and trigger applets wakeup. These timers are used to
refresh the sync task timeer itself. Thus it is important to take care to
always properly refresh them.

However, when there are some data to push, the reconnect timer is not
checked. It may be expired and not refreshed. In this case, an expired timer
may be used to the sync task, leading to a storm of wakeups. The sync task
is woken up in loop because its timer is in the past, waking up Peer applets
at each time.

To fix the issue, the peer's reconnect timer is now refresh to the default
reconnect timeout, if necessary, when there are some data to push.

This patch must be backported to all stable versions.

src/peers.c

@@ -3423,6 +3423,9 @@ struct task *process_peer_sync(struct task * task, void *context, unsigned int s
 								ps->flags &= ~PEER_F_HEARTBEAT;
 								/* Re-schedule another one later. */
 								ps->heartbeat = tick_add(now_ms, MS_TO_TICKS(PEER_HEARTBEAT_TIMEOUT));
+								/* Refresh reconnect if necessary */
+								if (tick_is_expired(ps->reconnect, now_ms))
+									ps->reconnect = tick_add(now_ms, MS_TO_TICKS(PEER_RECONNECT_TIMEOUT));
 								/* We are going to send updates, let's ensure we will
 								 * come back to send heartbeat messages or to reconnect.
 								 */