vcs: Support building commit ID / tagged version into binary

[silbinarywolf]

Why?

• It would help with debugging builds
• If I find builds years later, I know exactly what version they're at by comparing to my VCS history

What VCS should be supported?
Git first and foremost. However for gamedev, others use SVN, PlasticSCM and Perforce so maybe using a third-party library that works across these would be better?

Expectation

• Build Git version / commit ID into binary when publishing releases. (planning to make gmlgo publish)