[Paraview] CVS MPI compile failing

[John Biddiscombe]

> Oops. I was wrong. MPI_INCLUDE_PATH is indeed included in the top
> CMakeLists.txt file. VTK_INCLUDE_DIRS_SYSTEM include MPI_INCLUDE_PATH.
>   
This is very annoying (by the way), because if you change the path of 
mpi.h to use a different implementation, the whole of paraview gets 
rebuilt. I've done it about 4 times today, and I'm fed up with it :(

JB