My changes to test rpl_insert_id in 4.0 about replication of foreign_key_checks

have in fact no effect, because in 4.0 the slave always runs with --skip-innodb.
In 4.1, mysqld accepts option --innodb which can override --skip-innodb.
So I add this option to the test.
When the updated test (using InnoDB tables) from 4.0 will be merged
into 4.1, with this good .opt file, we'll have a meaningful test in 4.1.
Until then, the test in 4.1 will pass but be useless.
And in 4.0, it will stay useless forever.
("it" = the part of the test which tests replication of foreign_key_checks)

mysql-test/t/rpl_insert_id-slave.opt

+--innodb