fix tag in lookup_ct_def

I think this is the environment tag, not sure.
thinking about adding map from semantic locs to machine locs

locations as observable values should have machine addresses. adding a
new argument wherever required to injectiely map from semantic addresses
to these. hopefully will only show up in proofs...
continue working on getting compileCorrectnessTheory to build

(with handled expressions, references, etc.)
up to attempting to restate the main theorem (compile_val)