It is lossy, so should be requested explicitly, using a dedicated
fromPixmap factory function.
Deprecate the constructor and assignment operator, and make the
constructor explicit.
[ChangeLog][QtGui][QBitmap] Implicitly constructing and assigning
to a QBitmap from a QPixmap has been deprecated, and the respective
constructor has been made explicit. Use the fromPixmap factory
function instead.
Change-Id: I68ce85b26c901415137b664a1db687021d48bae0
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
861c4d8548