MINOR: peers: Add debugging information to "show peers".

This patch adds three counters to help in debugging peers protocol issues
to "peer" struct:
	->no_hbt counts the number of reconnection period without receiving heartbeat
	->new_conn counts the number of reconnections after ->reconnect timeout expirations.
	->proto_err counts the number of protocol errors.

(cherry picked from commit ec1c10b8391b5d1b54de2e95f9c170c9016fe680)
Signed-off-by: Willy Tarreau <w@1wt.eu>
diff --git a/include/types/peers.h b/include/types/peers.h
index 01b84b1..89962a3 100644
--- a/include/types/peers.h
+++ b/include/types/peers.h
@@ -68,6 +68,9 @@
 	unsigned int confirm;         /* confirm message counter */
 	uint32_t rx_hbt;              /* received heartbeats counter */
 	uint32_t tx_hbt;              /* transmitted heartbeats counter */
+	uint32_t no_hbt;              /* no received heartbeat counter */
+	uint32_t new_conn;            /* new connection after reconnection timeout expiration counter */
+	uint32_t proto_err;           /* protocol errors counter */
 	struct appctx *appctx;        /* the appctx running it */
 	struct shared_table *remote_table;
 	struct shared_table *last_local_table;