fix send_q stuck

src/etcp.c

@@ -393,7 +393,7 @@ static void input_queue_try_resume(struct ETCP_CONN* etcp) {
     size_t send_q_bytes = queue_total_bytes(etcp->input_send_q);
     size_t total_bytes = wait_ack_bytes + send_q_bytes;
 
-    if (total_bytes <= etcp->optimal_inflight) {
+    if (total_bytes <= etcp->optimal_inflight || send_q_bytes>0) {
         DEBUG_DEBUG(DEBUG_CATEGORY_ETCP, "[%s] resume callbacks: inflight_bytes=%d, input_len=%d", etcp->log_name, total_bytes, etcp->input_queue->total_bytes);
         queue_resume_callback(etcp->input_send_q);// вызвать лишний раз resume не страшно.
 //etcp_stats(etcp);