Rewrite of license-header.sh. Lots of new goodies:
- Fully POSIX compliant
- supports dash arguments (-u/--update, -c/--commit, -uc for both)
- can update year or malformed headers in-place now
- accounts for shell scripts
- exclusion of external files (e.g. sse2neon, my CMake modules/scripts)
- better, more extensible logic all around
Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/2780
crueter
d7cd7c6313