superbuild: fix `help()` calls in pvpython

* Ben Boeckel: python3-install-sysconfigdata-modules (common-superbuild!622)
* Ben Boeckel: fix_typo_mesa (common-superbuild!621)
* Ben Boeckel: fix_lz4_download_location (common-superbuild!620)
* Ben Boeckel: python-remove-excess-data (common-superbuild!613)
* Mathieu Westphal: adding_openvdb_deps (common-superbuild!617)
* Ben Boeckel: add-netcdf4-python (common-superbuild!619)

superbuild @ 83b78a67

-Subproject commit bb2ce821ec3292e682c9a23a3b6ba1a0175a7b63
+Subproject commit 83b78a674888730f7f512428602d8c46c3e2bf4d