When an aggregate function is used for a column in a SQL resultset then
it should ensure that the right data type is reported for that column.
This also concerns expressions when the returned column does not map
directly to a table column.

Test included for this.

Task-number: QTBUG-22038
Change-Id: I07487694c0ed393d46af06e232914fe923356a99
Reviewed-by: Mark Brand <mabrand@mabrand.nl>
Reviewed-by: Honglei Zhang <honglei.zhang@nokia.com>