Compiling VTK for POWER (ppc64le) PC

Hi!

I would like to compile VTK with the Python wrapping for linux-ppc64le running RHEL 7.4. Specifically for an AC922, which contains an IBM POWER9 PC, and 4*V100 Nvidia GPUs.

I know that VTK-m has been [built successfully for the architecture](https://developer.download.nvidia.com/video/gputechconf/gtc/2019/presentation/s9458-vtk-m-lessons-from-building-a-visualization-toolkit-for-massively-threaded-architectures-v2.pdf), but I'm not sure that provides a Python wrapper.

Could anyone provide any direction/pointers on how to compile for linux-ppc64le?

```
$ conda info
active environment : vtk_python
active env location : /home/tom/anaconda3/envs/vtk_python
shell level : 2
user config file : /home/tom/.condarc
populated config files : /home/tom/.condarc
conda version : 4.7.5
conda-build version : not installed
python version : 3.7.2.final.0
virtual packages : __cuda=10.1
base environment : /home/tom/anaconda3 (writable)
channel URLs : https://public.dhe.ibm.com/ibmdl/export/pub/software/server/ibm-ai/conda/linux-ppc64le
https://public.dhe.ibm.com/ibmdl/export/pub/software/server/ibm-ai/conda/noarch
https://conda.anaconda.org/conda-forge/linux-ppc64le
https://conda.anaconda.org/conda-forge/noarch
https://repo.anaconda.com/pkgs/main/linux-ppc64le
https://repo.anaconda.com/pkgs/main/noarch
https://repo.anaconda.com/pkgs/r/linux-ppc64le
https://repo.anaconda.com/pkgs/r/noarch
package cache : /home/tom/anaconda3/pkgs
/home/tom/.conda/pkgs
envs directories : /home/tom/anaconda3/envs
/home/tom/.conda/envs
platform : linux-ppc64le
user-agent : conda/4.7.5 requests/2.22.0 CPython/3.7.2 Linux/3.10.0-957.10.1.el7.ppc64le rhel/7.6 glibc/2.17
UID:GID : 1001:1001
netrc file : None
offline mode : False
```

The issue names no repository file, test, or build entry point. Start by reviewing the repository's setup and build instructions for VTK Python wheels, along with the available ppc64le and conda toolchain. Done would require a documented, reproducible path for compiling the Python-wrapped package on the stated platform.

索引モデルが issue の本文から書いたものです。