remove rpsubrs

remove rpsubrs

* libguile/tags.h: Remove rpsubrs (I chose to interpret the terse name
  as "recursive predicate subrs"). Just use gsubrs with rest arguments,
  or do a fold yourself.

* libguile/array-map.c (scm_i_array_equal_p): Do the comparison in
  order, why not.

* libguile/chars.c:
* libguile/eq.c:
* libguile/numbers.c:
* libguile/strorder.c: Add 0,2,1 gsubr wrappers for rpsubrs like eq?, <,
  etc.

* 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 rpsubr cases.

* test-suite/tests/numbers.test ("=", "<"): Turn a couple xfails into
  passes.