Add support for cleanup functions for data-constructed QImages

Add support for cleanup functions for data-constructed QImages

A QImage can be constructed with a provided buffer, that has to be
kept alive for the live-time of the QImage and all its copies.
Frameworks like CoreGraphics or Cairo offer a similar method of
creating image objects and also offer the ability to provide a callback
function that is called when the image is destroyed.

This patch adds this functionality to QImage by extending the
QImage constructors that take a raw image buffer pointer.

Change-Id: Ia6342408c560ef49b498c9e4664b4602febb0fcd
Reviewed-by: Samuel Rødal <samuel.rodal@nokia.com>
Reviewed-by: Michalina Ziemba <michalina.ziemba@nokia.com>
Reviewed-by: Gunnar Sletta <gunnar.sletta@nokia.com>