Untag values and indexes for all bytevector instructions

* libguile/vm-engine.c (bv-s8-ref, bv-s16-ref, bv-s32-ref, bv-s64-ref):
  Unbox index and return unboxed S32 value.
  (bv-s8-set!, bv-s16-set!, bv-s32-set!, bv-s64-set!): Unbox index and
  take unboxed S32 value.
  (bv-u8-ref, bv-u16-ref, bv-u32-ref, bv-u64-ref)
  (bv-s8-set!, bv-s16-set!, bv-s32-set!, bv-s64-set!): Likewise, but
  with unsigned values.
  (bv-f32-ref, bv-f32-set!, bv-f64-ref, bv-f64-set!): Use memcpy to
  access the value so we don't have to think about alignment.  GCC will
  inline this to a single instruction on architectures that support
  unaligned access.
* libguile/vm.c (vm_error_out_of_range_uint64)
  (vm_error_out_of_range_int64): New helpers.

* module/language/cps/slot-allocation.scm (compute-var-representations):
  All bytevector ref operations produce untagged values.

* module/language/cps/types.scm (define-bytevector-accessors): Update
  for bytevector untagged indices and values.

* module/language/cps/utils.scm (compute-constant-values): Fix s64
  case.

* module/language/tree-il/compile-cps.scm (convert): Box results of all
  bytevector accesses, and unbox incoming indices and values.

module/system/vm/disassembler.scm

@@ -108,7 +108,7 @@
     (define (parse-tail-word word type)
       (with-syntax ((word word))
         (case type
-          ((C32 I32 A32 B32 AU32 BU32 AF32 BF32)
+          ((C32 I32 A32 B32 AU32 BU32 AS32 BS32 AF32 BF32)
            #'(word))
           ((N32 R32 L32 LO32)
            #'((unpack-s32 word)))