[Paraview] error when building ffmpeg

[Ben Boeckel]

On Thu, Apr 13, 2017 at 08:26:22 -0400, David E DeMarle wrote:
> Turn on paraview_FROM_SOURCE_DIR

Note that the `master` and `5.3.0` branches now have
`paraview_SOURCE_SELECTION` and it should be set to `source`.

--Ben