Make sure rpl.rpl_innodb_mixed_dml passes even if rpl_mixed.dat is read-only.

This is important for a development environment where not all source files
are checked out.

mysql-test/suite/rpl/include/rpl_mixed_dml.inc

@@ -53,7 +53,7 @@ DELETE FROM t2 WHERE a = 2;
 --echo ******************** LOAD DATA INFILE ********************
 --exec cp ./suite/rpl/data/rpl_mixed.dat $MYSQLTEST_VARDIR/tmp/
 LOAD DATA INFILE '../tmp/rpl_mixed.dat' INTO TABLE t1 FIELDS TERMINATED BY '|' ;
---exec rm $MYSQLTEST_VARDIR/tmp/rpl_mixed.dat
+--remove_file $MYSQLTEST_VARDIR/tmp/rpl_mixed.dat
 SELECT * FROM t1;
 --source suite/rpl/include/rpl_mixed_check_select.inc
 --source suite/rpl/include/rpl_mixed_clear_tables.inc