* combine all patches for 1612 into a single file, with additional
comments to explain the rational.
* Add kahip decomposition variant.
* Add support for ARM64 architecture.
* filter instead of patching etc/config.*/settings. This eliminates
patch files for 1706, perhaps for the future as well.
* URLs at or before version 1612 have a different structure, so
provide a url_for_version implementation to handle this
f07ce6094e