When we drag a entry in TreeListBox, we execute a PaintDDCursor
which paints a "cursor" of a possible drag target (for example
to show where the entry will be moved to if we want to change the
order). The problem with this fuction is that it paints a line
directlly at that location, and that it uses invert raster
operation to draw a line. So to hide the line it just needs to
draw again. On MacOS this invertion causes a problem and draws
the whole area black, which is the cause of this bug.

So instead of inverting the drawing of the drag target cursor
has now been moved into the main Paint method, where it redraws
the whole entry, and if present, also the drag target cursor.
This means that all we need to do is Invalidate the entry,
which then just gets redrawn in a normal Paint pass.

One exception is still MacOS, which doesn't invalidate the entry,
but redraws the entry directly. DnD is MacOS is a bit different
as it is not async (if I understand correctly) so the invalidate
has no effect.

Change-Id: I8542f47940a3b90114ea4bbbac57fd303ca3434b
Reviewed-on: https://gerrit.libreoffice.org/70521
Tested-by: Jenkins
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>