- 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
* removed the tags as per comment in PR# 4749
* addressed above comments
* changed fortran compiler.
* added proxy application tags.
* added tags by removing them from description.
* addressed comments
* used join_path instead of path concat.
* addressed comments
* removed string formatting for LDFLAGS.