And finally nothing inside libkwineffects, libkwinglutils,
libkwinxrenderutils and kwineffect and kwin core uses KWin::display.
We are finally XLib free!

This change drops KWin::display and removes the include to QX11Info from
kwinglobals.h. And the libraries no longer need to link X11Extras. Due
to that removal a few seeming unrelated changes are required to add the
include where needed and linkage to X11Extras.

The biggest change is to x11 platform plugin which still needs the
display and caches it in the Platform and passes it to various places in
a way that the code doesn't need to be adjusted.