Logging: Free the ringbuffer in child processes created with ctdb_fork()

At the moment the log ringbuffer is duplicated in every child process.
Althought it is copy-on-write we want to see if it is contributing to
out-of-memory situations when there are a lot of children.

The ringbuffer isn't accessible from any of the children anyway...

Signed-off-by: Martin Schwenke <martin@meltin.net>

(This used to be ctdb commit a82d3ec12f0fda16d6bfa8442a07595de897c10e)

ctdb/common/ctdb_fork.c

@@ -59,6 +59,9 @@ pid_t ctdb_fork(struct ctdb_context *ctdb)
 			ctdb_restore_scheduler(ctdb);
 		}
 		ctdb->can_send_controls = false;
+
+		ctdb_log_ringbuffer_free();
+
 		return 0;
 	}