CLEANUP: stconn: use a single function to know if SC may send to SE

sc_is_send_allowed() is now used everywhere instead of the combination
of cs_tx_endp_ready() && !cs_tx_blocked(). There's no place where we
need them individually thus it's simpler. The test was placed in cs_util
as we'll complete it later.
diff --git a/include/haproxy/cs_utils.h b/include/haproxy/cs_utils.h
index 9f5463d..22b21b2 100644
--- a/include/haproxy/cs_utils.h
+++ b/include/haproxy/cs_utils.h
@@ -341,4 +341,14 @@
 	}
 }
 
+/* indicates if the connector may send data to the endpoint, that is, the
+ * endpoint is both willing to receive data and ready to do so. This is only
+ * used with applets so there's always a stream attached to this connector.
+ */
+__attribute__((warn_unused_result))
+static inline int sc_is_send_allowed(const struct stconn *sc)
+{
+	return cs_tx_endp_ready(sc) && !cs_tx_blocked(sc);
+}
+
 #endif /* _HAPROXY_CS_UTILS_H */
diff --git a/src/applet.c b/src/applet.c
index fe1fc62..1af0dbd 100644
--- a/src/applet.c
+++ b/src/applet.c
@@ -246,7 +246,7 @@
 	if (rate >= 100000 && app->call_rate.prev_ctr && // looped more than 100k times over last second
 	    ((b_size(sc_ib(cs)) && se_fl_test(app->sedesc, SE_FL_RXBLK_BUFF)) || // asks for a buffer which is present
 	     (b_size(sc_ib(cs)) && !b_data(sc_ib(cs)) && se_fl_test(app->sedesc, SE_FL_RXBLK_ROOM)) || // asks for room in an empty buffer
-	     (b_data(sc_ob(cs)) && cs_tx_endp_ready(cs) && !cs_tx_blocked(cs)) || // asks for data already present
+	     (b_data(sc_ob(cs)) && sc_is_send_allowed(cs)) || // asks for data already present
 	     (!b_data(sc_ib(cs)) && b_data(sc_ob(cs)) && // didn't return anything ...
 	      (sc_oc(cs)->flags & (CF_WRITE_PARTIAL|CF_SHUTW_NOW)) == CF_SHUTW_NOW))) { // ... and left data pending after a shut
 		stream_dump_and_crash(&app->obj_type, read_freq_ctr(&app->call_rate));
diff --git a/src/conn_stream.c b/src/conn_stream.c
index 9ad5258..e3c2066 100644
--- a/src/conn_stream.c
+++ b/src/conn_stream.c
@@ -1951,8 +1951,7 @@
 	 * appctx but in the case the task is not in runqueue we may have to
 	 * wakeup the appctx immediately.
 	 */
-	if ((cs_rx_endp_ready(cs) && !cs_rx_blocked(cs)) ||
-	    (cs_tx_endp_ready(cs) && !cs_tx_blocked(cs)))
+	if ((cs_rx_endp_ready(cs) && !cs_rx_blocked(cs)) || sc_is_send_allowed(cs))
 		appctx_wakeup(__sc_appctx(cs));
 	return 0;
 }
diff --git a/src/stream.c b/src/stream.c
index c0e49b6..e6b1978 100644
--- a/src/stream.c
+++ b/src/stream.c
@@ -1543,13 +1543,11 @@
 	 * handled at the latest moment.
 	 */
 	if (sc_appctx(scf)) {
-		if ((cs_rx_endp_ready(scf) && !cs_rx_blocked(scf)) ||
-		    (cs_tx_endp_ready(scf) && !cs_tx_blocked(scf)))
+		if ((cs_rx_endp_ready(scf) && !cs_rx_blocked(scf)) || sc_is_send_allowed(scf))
 			appctx_wakeup(__sc_appctx(scf));
 	}
 	if (sc_appctx(scb)) {
-		if ((cs_rx_endp_ready(scb) && !cs_rx_blocked(scb)) ||
-		    (cs_tx_endp_ready(scb) && !cs_tx_blocked(scb)))
+		if ((cs_rx_endp_ready(scb) && !cs_rx_blocked(scb)) || sc_is_send_allowed(scb))
 			appctx_wakeup(__sc_appctx(scb));
 	}
 }