Fix contification of non-recursive closures

Fix contification of non-recursive closures

* module/language/cps/contification.scm (compute-contification): When
  eliding let-bound functions, also record the cont that declares the
  function.
  (apply-contification): Instead of reifying ($values ()) gotos instead
  of the elided function, inline the body that binds the function
  directly.  This ensures that the function gets contified in its own
  scope.