[Plasma] Qt patch for desktop icon papercut

[Eike Hein]

'lo dear packagers,

the Plasma team recommends applying the following patch to both Qt
5.9 and Qt 5.10 at your convenience:

https://codereview.qt-project.org/#/c/215939/

This fixes a bug causing the wrong desktop icon to look hovered
after dragging an icon on the desktop (the top-left icon instead
of the just-dropped one).

This is not a serious bug. The patch may also fix similar issues
in other UIs, though.

The patch should find its way into the next Qt 5.9.x and 5.10.x
releases.


Cheers,
Eike