Fix lisp cond expand

[vinc]

With the following macro for eq?

(var eq?
  (macro args `(equal? ,@args)))

The macro was not expanded while expanding cond

> (cond ((equal? "a" "a") "oh noes"))
"oh noes"

> (cond ((eq? "a" "a") "oh noes"))
Error: Expected first argument to be a function

[vinc]

There might be a more general solution during eval to expand any macros left.