- in many files, regular strings were used in places where raw strings
should've been used.
- convert these to raw strings and get rid of new flake8 errors
- 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
* Add package for multitail@6.4.2
Lightly tested on CentOS 7.
* Responde to feedback/comments
Use `install_targets` to specify PREFIX= and DESTDIR= instead of
hacking away at the Makefile. Expand commentary about "Why?".
Use `headers.include_flags` and `libs.ld_flags` to avoid explicitly
setting `-L` and `-I` when hacking away at the Makefile.
