Start detecting coderef/str/callsite refs to fix.

They need fixing up in the case some some inter-compilation-unit
inlines. For now, just complains (so we know that's actually the
problem).
Ensure args always go in the right place.

That is, we should always have | registers | args |. We got this wrong
in the inline case until now, overlaying the args buffer with some of
the inlinee's registers.