GCS_MAVLink: correct is_streaming check and update of is-streaming mask

libraries/GCS_MAVLink/GCS.h

@@ -378,7 +378,7 @@ public:
         return GCS_MAVLINK::active_channel_mask() & (1 << (chan-MAVLINK_COMM_0));
     }
     bool is_streaming() const {
-        return GCS_MAVLINK::streaming_channel_mask() & (1 << (chan-MAVLINK_COMM_0));
+        return sending_bucket_id != no_bucket_to_send;
     }
 
     mavlink_channel_t get_chan() const { return chan; }

libraries/GCS_MAVLink/GCS_Common.cpp

@@ -1659,6 +1659,12 @@ void GCS_MAVLINK::send_message(enum ap_message id)
 {
     if (id == MSG_HEARTBEAT) {
         save_signing_timestamp(false);
+        // update the mask of all streaming channels
+        if (is_streaming()) {
+            GCS_MAVLINK::chan_is_streaming |= (1U<<chan-MAVLINK_COMM_0);
+        } else {
+            GCS_MAVLINK::chan_is_streaming &= ~(1U<<chan-MAVLINK_COMM_0);
+        }
     }
 
     pushed_ap_message_ids.set(id);