Remove file from slave

The binlog file is now always opened when it is needed and closed
when we are finished with it. That will remove any potential
file concurrency issues between different threads dealing with
the same slave.

server/modules/include/blr.h

@@ -301,7 +301,9 @@ typedef struct router_slave {
 	char		binlogfile[BINLOG_FNAMELEN+1];
 					/*< Current binlog file for this slave */
 	char		*uuid;		/*< Slave UUID */
+#ifdef BLFILE_IN_SLAVE
 	BLFILE		*file;		/*< Currently open binlog file */
+#endif
 	int		serverid;	/*< Server-id of the slave */
 	char		*hostname;	/*< Hostname of the slave, if known */
 	char		*user;		/*< Username if given */