BUG/MINOR: contrib/spoa_example: Don't reset the status code during disconnect

When the connection is closed by HAProxy, the status code provided in the
DISCONNECT frame is lost. By retransmitting it in the agent's reply, we are sure
to have it in the SPOE logs.

This patch may be backported in 1.8.
diff --git a/contrib/spoa_example/spoa.c b/contrib/spoa_example/spoa.c
index d7486a4..7b40e81 100644
--- a/contrib/spoa_example/spoa.c
+++ b/contrib/spoa_example/spoa.c
@@ -1474,7 +1474,6 @@
 			if (client->status_code != SPOE_FRM_ERR_NONE)
 				LOG(client->worker, "<%lu> Peer closed connection: %s",
 				    client->id, spoe_frm_err_reasons[client->status_code]);
-			client->status_code = SPOE_FRM_ERR_NONE;
 			goto disconnect;
 	}