Fix check for extracting var from definition

[zampino]

Fixes #499. At present, a user defined macro which starts with def and expands to code like

(defmacro defmy [name body]
  `(do 
     (def ~name ~body) 
     return-some-val))

(defmy stuff bla)

when called produces a cell result wrapped in a {::clerk/var-from-def #'stuff} while the intended return value is actually discarded.

[mk]

The intent here was to actually account for user-defined macros that are like defs, so more than just those three concrete instances.

[zampino]

we could check the returned value is a var of the same name as the one inferred by the analyzer, to decide when to do the wrapping.