Fix: bug in VTK package (#9431)
Fix: bug in VTK package (#9431)

* Fix: bug in VTK package

Fix for issue 9423 (https://github.com/spack/spack/issues/9423): compilers other than clang don't have the `is_apple` property.

* VTK package: removing trailing whitespace

So flake8 stops complaining.

iulian787/spack,LLNL/spack,iulian787/spack,iulian787/spack,LLNL/spack,LLNL/spack,LLNL/spack,iulian787/spack,LLNL/spack,iulian787/spack