use private linkage where possible
use private linkage where possible

Change-Id: Iaf326a51e93ec334c02de07d8cd254998e73ce46
Reviewed-by: Joerg Bornemann <47777b9406dbddd02a3fdca8341789a013805a11@digia.com>

kobolabs/qtwinextras,kobolabs/qtwinextras