eval.c closures are now applicable smobs, not tc3s

eval.c closures are now applicable smobs, not tc3s

* libguile/debug.c (scm_procedure_name): Remove a SCM_CLOSUREP case and
  some dead code.
  (scm_procedure_module): Remove. This was introduced a few months ago
  for the hygienic expander, but now it is no longer needed, as the
  expander keeps track of this information itself.

* libguile/debug.h: Remove scm_procedure_module.

* libguile/eval.c: Instead of using tc3 closures, define a "boot
  closure" applicable smob type, and represent closures with that. The
  advantage is that after eval.scm is compiled, boot closures take up no
  address space (besides a smob number) in the runtime, and require no
  special cases in procedure dispatch.

* libguile/eval.h: Remove the internal functions scm_i_call_closure_0
  and scm_closure_apply, and the public function scm_closure.

* libguile/gc.c (scm_storage_prehistory): No tc3_closure displacement
  registration.
  (scm_i_tag_name): Remove closure case, and a dead cclo case.

* libguile/vm.c (apply_foreign):
* libguile/print.c (iprin1):
* libguile/procs.c (scm_procedure_p, scm_procedure_documentation);
* libguile/evalext.c (scm_self_evaluating_p):
* libguile/goops.c (scm_class_of): Remove tc3_closure/tcs_closure cases.
* libguile/hash.c (scm_hasher):

* libguile/hooks.c (scm_add_hook_x): Use new scm_i_procedure_arity.

* libguile/macros.c (macro_print): Print all macros using the same code.
  (scm_macro_transformer): Return any procedure, not just programs.

* libguile/procprop.h:
* libguile/procprop.c (scm_i_procedure_arity): Instead of returning a
  list that the caller has to parse, have the same prototype as
  scm_i_program_arity. An incompatible change, but it's an internal
  function anyway.
  (scm_procedure_properties, scm_set_procedure_properties)
  (scm_procedure_property, scm_set_procedure_property): Remove closure
  cases, and use scm_i_program_arity for arity.

* libguile/procs.h (SCM_CLOSUREP, SCM_CLOSCAR, SCM_CODE)
  (SCM_CLOSURE_NUM_REQUIRED_ARGS, SCM_CLOSURE_HAS_REST_ARGS)
  (SCM_CLOSURE_BODY, SCM_PROCPROPS, SCM_SETPROCPROPS, SCM_ENV)
  (SCM_TOP_LEVEL): Remove these macros that pertain to boot closures
  only. Only eval.c should know abut boot closures.
* libguile/procs.c (scm_closure_p): Remove this function. There is a
  simple stub in deprecated.scm now.
  (scm_thunk_p): Use scm_i_program_arity.
* libguile/tags.h (scm_tc3_closure): Remove. Yay, another tc3 to play
  with!
  (scm_tcs_closures): Remove.

* libguile/validate.h (SCM_VALIDATE_CLOSURE): Remove.

* module/ice-9/deprecated.scm (closure?): Add stub.

* module/ice-9/documentation.scm (object-documentation)
* module/ice-9/session.scm (help-doc, arity)
* module/oop/goops.scm (compute-getters-n-setters)
* module/oop/goops/describe.scm (describe)
* module/system/repl/describe.scm (display-object, display-type):
  Remove calls to closure?.