Source information goes on the $continue, not the $cont.

Source information goes on the $continue, not the $cont.

* module/language/cps.scm ($continue, $cont): Put source information on
  the $continue, not on the $cont.  Otherwise it is difficult for CPS
  conversion to preserve source information.
  ($fun): Add a src member to $fun.  Otherwise we might miss the source
  info for the start of the function.

* .dir-locals.el:
* module/language/cps/arities.scm:
* module/language/cps/closure-conversion.scm:
* module/language/cps/compile-rtl.scm:
* module/language/cps/constructors.scm:
* module/language/cps/contification.scm:
* module/language/cps/dfg.scm:
* module/language/cps/elide-values.scm:
* module/language/cps/reify-primitives.scm:
* module/language/cps/slot-allocation.scm:
* module/language/cps/verify.scm:
* module/language/tree-il/compile-cps.scm: Update the whole CPS world
  for this change.