Add test for SQLDescribeCol with cbColNameMax == 0

SQLDescribeCol can return the length required for the name passing 0 as
cbColNameMax. This is not working with current code.

Signed-off-by: Frediano Ziglio <freddy77@gmail.com>
Fix SQLDescribeCol with cbColNameMax == 0

This condition is just to get column name but didn't return correct
information.

Signed-off-by: Frediano Ziglio <freddy77@gmail.com>