- store_path() previously only worked for cross compilation packages, we
remove this assumption here
- Add CROSS_GCC_LIB variable which points to where gcc libs/headers are
located
- Add gcc libs/headers to our CROSS_*_PATH environment variables
- Check that all directories in CROSS_*_PATH are sane
- Clearer and more accurate prose
- Pin `guix pull' to commit rather than branch
- Just use `use-module' instead of `define-module'
- Use `bash-minimal' instead of `bash'
- Remove unneeded `tcsh' from manifest
- Explicitly use `python-3.7'
- Add comments about how {native,cross}-toolchains are produced and
why
