MINOR: stconn: Add functions to set/clear SE_FL_EXP_NO_DATA flag from endpoint

se_expect_data() and se_expect_no_data() should be used from the endpoint to
inform upper layer it expects data or not from the opposite endpoint.
diff --git a/include/haproxy/stconn.h b/include/haproxy/stconn.h
index 10395ac..27e6107 100644
--- a/include/haproxy/stconn.h
+++ b/include/haproxy/stconn.h
@@ -105,6 +105,16 @@
 		se_fl_set(se, SE_FL_ERR_PENDING);
 }
 
+static inline void se_expect_no_data(struct sedesc *se)
+{
+	se_fl_set(se, SE_FL_EXP_NO_DATA);
+}
+
+static inline void se_expect_data(struct sedesc *se)
+{
+	se_fl_clr(se, SE_FL_EXP_NO_DATA);
+}
+
 /* stream connector version */
 static forceinline void sc_ep_zero(struct stconn *sc)
 {