[Core Port Req.] Virtual X68000

### Upstream info
- [Website](https://www.vx68k.org/vx68k)
- Target platforms: Linux, macOS, and other Unices
- [Source repo](https://bitbucket.org/kazssym/libvm68k/src)
- Language(s): C++
- License: GPLv3+

Alternatives:
- [PX68K](https://github.com/hissorii/px68k) (in Japanese) in C/C++; no license, though the author granted RetroArch distribution rights