add missing EXPORT decl

Change-Id: I5b725fe7f0abfc85c3df7b06c96ec3a5fb54b934
Sanity-Review: Qt Sanity Bot <qt_sanitybot@qt-project.org>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>