Port Zoom effect to XCB and some small improvements

* use xcb_fixes_foo
* drop QX11Info - we don't need it in the effects
* use QScopedPointer for GLTexture/XRenderPicture
* remove commented code
* use kDebug instead of qDebug

Of course XCursor library is still used as there is no XCB replacement.
What could be considered is adding a getCursor hook into the
EffectsHandler as also the ScreenShot Effect is getting the cursor and
using XCursor doesn't seem future proof to me ;-)

Sorry for putting everything into one commit.

REVIEW: 109083