For backwards compatibility, we also `#include "tox_options.h"` in
`tox.h`, but in 0.3.0 we can break that so most toxcore client code
doesn't need the options, only the part that creates the instance.
Used by NetBSD, but we build on Alpine Linux for speed. Separately, we
will build on NetBSD without pkgsrc, to see whether it compiles and runs
there. That VM build is more expensive and harder to debug, so we keep
the pkgsrc Linux build for development.
iphydf