- configure with the arch + package only for the prefix.
  When OPAL_PREFIX is unset, yields this type of information:

      Prefix: /linux64Gcc/openmpi-4.0.3
      Libdir: /linux64Gcc/openmpi-4.0.3/lib

  This ensures that the final binaries do not have the original build
  location, which makes for more reliable testing before shipping.

ENH: improve handling of header-only CGAL

- test for existence now also checks our cached build information
  for header-only configuration

- cleanup build artifacts from boost (in-source build).
  Skip install of generated man, info, doc pages.
  These are usually browsed/searched elsewhere anyhow.