Some packages had incorrect checksums because they needed to be
downloaded from a new place or the package needed tweaking somehow.
These packages to sha256 and the new checksums have been verified by
fetching over https.
- remove the old LGPL license headers from all files in Spack
- add SPDX headers to all files
- core and most packages are (Apache-2.0 OR MIT)
- a very small number of remaining packages are LGPL-2.1-only
* Change path to CMakeLists.txt to be relative to root, not pwd
* Changes requested during code review
* Revert back to old naming of root_cmakelists_dir
* Make relative directory more clear in docs
* Revert change causing build_type AttributeError
* Fix forgotten abs_path var
* Update CLHEP with new relative path
* Update more packages with new root_cmakelists_dir syntax
