Description:
Fix an issue with INSERT query.

SOLUTION:
This issue is because  Group_check::check_expression() is
being called before Item_field::fix_fields() and setup_group().

In Group_check::check_expression() if GROUP BY clause is having
value of type Item::INT_ITEM then return false.

Change-Id: I62b3b1f8f3e3ad5a35defd27d66a9ab8a07b1c23