[Module] ParaView can't switch between nvidia and mesa using only LD_LIBRARY_PATH anymore.

When building with mesa, as expected, we need to do the following to use it :

LD_LIBRARY_PATH=/path/to/llvm/install/lib/:/path/to/mesa/install/lib ./bin/paraview
Help->About : lvmpipe ...

It was then still possible to use nvidia this way :

LD_LIBRARY_PATH= ./bin/paraview
Help->About : Nvidia ...

But now it fails with :

./bin/paraview: error while loading shared libraries: libLLVMX86Disassembler.so.7: cannot open shared object file: No such file or directory

The solution is to use LD_PRELOAD like this :

LD_LIBRARY_PATH=/path/to/llvm/install/lib/:/path/to/mesa/install/lib  LD_PRELOAD=/usr/lib/libGL.so ./bin/paraview

I'm not sure if it is expected. @ben.boeckel @cory.quammen @jpouderoux