Prepare superbuild for adding NVIDIA IndeX libraries for ParaView 5.9
Things to adapt after the NVIDIA IndeX libraries have been shipped: - Run extract-index.sh and update MD5 checksums to those of the generated files. - Update the date in "nvidia-index-libs-5.9.00000000". - Move DEFAULT from 2.4 to 5.9. This commit also adds POWER9 (ppc64le) libraries.