Remove Widgets dependency for QNX

Changes.txt says that with Qt 5.2.0 dependency for
Widgets have been removed for touch based platforms.
But QNX is also a touch based platform and its missing.

Change-Id: I140842d4501422537175ac5acb07beebe994f0eb
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>