We'd like to use a consistent checksum scheme everywhere so that we can:
a) incorporate archive checksums into our specs and have a
consistent hashing algorithm across all specs.
b) index mirrors with a consistent type of checksum, and not one that
is dependent on how spack packages are written.
- [x] convert existing md5, sha224, sha512, sha1 checksums to sha256
- 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 GCC 7
* Allow users to build subset of GCC compilers with multi-value variant.
* Add comment explaining what 'all' actually means
* More specific golang support
* Only require Zip when building Java
* Comment out provide directives that don't currently work
* Add Ada support
* Use conflicts directive
* Fix joining of languages
* Need special flag to build jit
* Explicitly declare GNAT download extension
* Import tty, update lib64 to lib
* BRIG and Go are not supported on macOS
* Simplify formatting and imports
* JIT patch required for newer versions as well
