Meant to use QPointer not QScopedPointer.

Note that the crash reported in the bug # below was supposed to be addressed by
the original commit db0ee97f. However, QScopedPointer causes the same problems
as using a plain pointer or creating the print dialog on the stack. For further
detailsi details, read http://blogs.kde.org/node/3919.

BUG: 289453