remove asubrs

* libguile/tags.h (scm_tcs_subrs, scm_tc7_asubr): Remove definitions.

* libguile/goops.c (scm_class_of)
* libguile/procprop.c (scm_i_procedure_arity)
* libguile/procs.c (scm_thunk_p)
* libguile/vm.c (apply_foreign): Remove cases for asubrs.

* libguile/array-map.c: Gut all of the optimizations, because there are
  no more asubrs, soon won't be rpsubrs, and all of this should happen
  on the Scheme level, ideally.

libguile/procprop.c

@@ -56,7 +56,6 @@ scm_i_procedure_arity (SCM proc)
     case scm_tc7_cxr:
       a += 1;
       break;
-    case scm_tc7_asubr:
     case scm_tc7_rpsubr:
       r = 1;
       break;