Disable WinCE from QtPIM build.

This was broken a while ago in qt5.git. The relevant revert
is waiting to be integrated to qt5.

Task-number: QTBUG-42763
Change-Id: I0e0200d4aa1a6dc195ab4aa0edb723a5a5972b00
Reviewed-by: Alex Blasche <alexander.blasche@theqtcompany.com>
Reviewed-by: Simo Fält <simo.falt@digia.com>