c claims to implement print/assert writers but doesn't really

[Gankra]

the emitted code is gibberish. i stubbed it out and never went back to it, whoops!

[Gankra]

NB the annoying/big thing to do here is implement "kdl type => c format specifier" translation. Right now we just %d everything!

Also picking the appropriate assert function (ideally a release assert).