Methods:
- Item_user_var_as_out_param::print_for_load()
- sql_exchange::escaped_given(void)

Parameters:
- sql_exchange in write_execute_load_query_log_event()
- sql_exchange in mysql_load()
- sql_exchange in Load_log_event::Load_log_event()

Also, removing cast to "char*" in a few places in
Load_log_event::Load_log_event()