WIP: Patch libjpeg linking issue

I don't think there's a way to merge this in via a merge request) without merging into an existing branch. It really needs to be a commit right after the v5.5.2 tag. So either the superbuild needs a branch I can target, or the branch will have to be pushed directly.

The added patch enables cmake policy CMP0074 on the paraview and vtk builds, which allows for providing JPEG_ROOT (among other things) to the builds via cmake or environment variable. There are problems we've encountered where paraview builds against the system version of libjpeg when it should be building a provided version. Paraview then ends up linking (at various dependency levels) against both the system and the provided versions of the lib. Allowing JPEG_ROOT allows us to get around that issue.