Flush Aria WAL log before copying the log file.

Author: mariadb-andrzejjarzabek

storage/maria/ma_backup.cc

@@ -143,6 +143,8 @@ namespace
         return 1;
       if (copy_control_file())
         return 1;
+      if(translog_flush(translog_get_horizon()))
+        return 1;
       if (copy_logs())
         return 1;
       return 0;