Rewrite make.sh to make it shorter, faster and more portable

- Remove bashisms (use posix shell)
- Use only two space indentation (no mixed tabs)
- Honor $0 and autogenerate help message
- Correct use of exported and local vars
- Simplify spaguetti (-30LOC)
- Update copyright year
- Quote all vars to avoid command injection
- Cache uname value and allow to override it
- Honor user environment
- Support MAKE_JOBS (by default is 4)
2 files changed