Follow-up fix to MDEV-14705: Flush log at shutdown

In commit e7f4e61
the call fil_flush_file_spaces(FIL_LOG) is necessary.
Tablespaces will be flushed as part of the redo log
checkpoint, but the redo log will not necessarily
be flushed, depending on innodb_flush_method.

storage/innobase/log/log0log.cc

@@ -3463,6 +3463,9 @@ logs_empty_and_mark_files_at_shutdown(void)
 
 		mutex_exit(&log_sys->mutex);
 
+		/* Ensure that all buffered changes are written to the
+		redo log before fil_close_all_files(). */
+		fil_flush_file_spaces(FIL_LOG);
 	} else {
 		lsn = srv_start_lsn;
 	}

storage/xtradb/log/log0log.cc

@@ -3780,6 +3780,9 @@ logs_empty_and_mark_files_at_shutdown(void)
 
 		mutex_exit(&log_sys->mutex);
 
+		/* Ensure that all buffered changes are written to the
+		redo log before fil_close_all_files(). */
+		fil_flush_file_spaces(FIL_LOG);
 	} else {
 		lsn = srv_start_lsn;
 	}