[Paraview] The DISTDIR variable is expanded twice when installing PointSpriteDemo

[François Bissey]

> Thanks for reporting this. It has been fixed on master and will be
> included in 3.8.1 release.
> 
> http://paraview.org/Bug/view.php?id=10815
> 
What about the double expansion of DESTDIR? The bug only mention respecting
BUILD_EXAMPLES.

Francois