fix warning messages from pedantic flag in C compilation

[nrlucaroni]

(this may be resolved in switching to c-types) (see Issue #3 )

[rgrinberg]

+1 for switching to ctypes. But I think it would be best to do it once stub generation is settled.

[nrlucaroni]

Good to know, I've been wanting a reason to look into ctypes, but I guess I'll wait a bit.