Leopard.
The change_user test failed because results of some statements
depended on platform and server build flags.
subselect_notembedded failure was a result of a bad merge from 5.0.
Fixed the corresponding test cases.
The problem is that currently there is no way to test the behavior
of the mysql_change_user() function using the mysqltest suite because
there is no internal command for it.
The solution is to introduce a change_user command that can be used
to test aspects of the MySQL client function mysql_change_user().
