Fix lua bindings and build system
The current lua bindings have no build system or test support at all and substantially redeclare structures from hammer.h in hammer.lua; since they haven't been updated in 7 years they have probably fallen out of sync with the library. Ideally those declarations should be autogenerated at build time rather than needing manual maintenance, or should be verified to depend only on stable, public interfaces; in either case they should have test suite coverage.
Urgency is low; I'm not sure anyone's actually using this anyway, and work on it now would just have to be replaced for the new autoconf build system anyway. I'm writing the ticket to document that it's currently in dubious condition and the absence of a completely novel lua build system in the initial autoconf release is not a regression.