QODBC: char fields treated as byte arrays if database does not support unicode conversions

The QODBC driver treats char fields as byte arrays if the connected database does not support unicode conversions.

This will eventually lead to errors when Qt tries to update a char field with binary data.

The QODBC driver seems to have code to handle string conversions in case the database does not support unicode, so it looks suspicious that the QODBC driver treats char fields as byte arrays by default in this case.