[Paraview] Forcing a Qt version

[John Biddiscombe]

Renato
> by modifying my PATH before the first time I 
> run cmake on an empty build directory.
>   
I think the big clue here is the "empty build directory". I use multiple 
Qt versions and CMake is quite pathological about them. If you try to 
switch from one version to another, you really need to wipe the build 
directory. What I usually do is edit the cache files, by doing a search 
replace for all paths from the old Qt and replace them with the new. But 
even this still sometimes manages to confuse CMake due to configured 
"other files" all over the place. To be sure you really have to wipe all 
cache stuff and make sure the new QMake is on your path before rerunning 
ccmake.

0.02

JB