add missing leave_function()

libssh/channels.c

@@ -2161,8 +2161,10 @@ int channel_poll(ssh_channel channel, int is_stderr){
     }
   }
 
-  if (buffer_get_rest_len(stdbuf) > 0)
-    return buffer_get_rest_len(stdbuf);
+  if (buffer_get_rest_len(stdbuf) > 0){
+    leave_function();
+  	return buffer_get_rest_len(stdbuf);
+  }
 
   if (channel->remote_eof) {
     leave_function();