dynamic-wind in terms of wind and unwind; remove <dynwind>, @dynamic-wind

* doc/ref/compiler.texi: Remove mention of <dynwind>.
* libguile/eval.c (eval): Remove SCM_M_DYNWIND case.
* libguile/expand.c: Remove scm_sym_at_dynamic_wind.
* libguile/memoize.c (do_wind, do_unwind): A couple of hacky subrs.  If
  we see a wind or unwind primcall, we expand to a call of a quoted subr
  value.  It works and removes a kind of memoized value from the
  interpreter.  For the compiler,primcalls to wind and unwind are
  handled specially.
  (MAKMEMO_DYNWIND): Remove.
  (scm_tc16_memoizer): Remove.  Yay!
  (memoize): Remove speculative lookup for toplevels to see if they are
  memoizers: there are no more memoizers.  Memoize calls to the wind and
  unwind primitives.
  (m_dynamic_wind): Remove.
  (unmemoize): Remove dynwind case.
  (scm_init_memoize): Add wind and unwind local definitions.

* module/ice-9/boot-9.scm (dynamic-wind): Reimplement in terms of "wind"
  and "unwind" primitives.  These primitives are not exposed to other
  modules.

* module/ice-9/eval.scm (primitive-eval): Remove dynwind case.
* module/language/scheme/decompile-tree-il.scm (do-decompile):
  (choose-output-names): Remove dynwind cases.

* module/language/tree-il.scm: Remove <dynwind>.  Yaaay!

* module/language/tree-il/analyze.scm (analyze-lexicals): Remove dynwind
  cases.

* module/language/tree-il/compile-glil.scm (*primcall-ops*): Add wind
  and unwind.
  (flatten-lambda-case): Remove dynwind case.  Yay!

* module/language/tree-il/cse.scm (cse):
* module/language/tree-il/debug.scm (verify-tree-il):
* module/language/tree-il/effects.scm (make-effects-analyzer):
* module/language/tree-il/peval.scm (singly-valued-expression?, peval):
  Remove <dywind> cases.  Inline primcalls to dynamic-wind.  Add
  constant folding for thunk?.

* module/language/tree-il/primitives.scm (*interesting-primitive-names*):
  Remove @dynamic-wind, and add procedure? and thunk?.
  (*effect+exception-free-primitives*): Add procedure? and thunk?.
  (*multiply-valued-primitives*): Remove @dynamic-wind.
  Remove @dynamic-wind expander.

* test-suite/tests/peval.test ("partial evaluation"): Update tests for
  dynwind desugaring.

module/language/tree-il/primitives.scm

@@ -41,7 +41,6 @@
     call-with-current-continuation
     call/cc
     dynamic-wind
-    @dynamic-wind
     values
     eq? eqv? equal?
     memq memv
@@ -51,6 +50,8 @@
     not
     pair? null? list? symbol? vector? string? struct? number? char? nil?
 
+    procedure? thunk?
+
     complex? real? rational? inf? nan? integer? exact? inexact? even? odd?
 
     char<? char<=? char>=? char>?
@@ -176,6 +177,7 @@
     eq? eqv? equal?
     not
     pair? null? list? symbol? vector? struct? string? number? char?
+    procedure? thunk?
     acons cons cons* list vector))
 
 ;; Primitives that don't always return one value.
@@ -185,7 +187,6 @@
     call-with-current-continuation
     call/cc
     dynamic-wind
-    @dynamic-wind
     values
     call-with-prompt
     @abort abort-to-prompt))
@@ -533,38 +534,6 @@
 (hashq-set! *primitive-expand-table* 'eqv?   maybe-simplify-to-eq)
 (hashq-set! *primitive-expand-table* 'equal? maybe-simplify-to-eq)
 
-(hashq-set! *primitive-expand-table*
-            '@dynamic-wind
-            (case-lambda
-              ((src pre expr post)
-               (let* ((PRE (gensym "pre-"))
-                      (POST (gensym "post-"))
-                      (winder (make-lexical-ref #f 'winder PRE))
-                      (unwinder (make-lexical-ref #f 'unwinder POST)))
-                 (define (make-begin0 src first second)
-                   (make-let-values
-                    src
-                    first
-                    (let ((vals (gensym "vals ")))
-                      (make-lambda-case
-                       #f
-                       '() #f 'vals #f '() (list vals)
-                       (make-seq
-                        src
-                        second
-                        (make-primcall #f 'apply
-                                       (list
-                                        (make-primitive-ref #f 'values)
-                                        (make-lexical-ref #f 'vals vals))))
-                       #f))))
-                 (make-let src '(pre post) (list PRE POST) (list pre post)
-                           (make-seq src
-                                     (make-call src winder '())
-                                     (make-begin0
-                                      src
-                                      (make-dynwind src winder expr unwinder)
-                                      (make-call src unwinder '()))))))))
-
 (hashq-set! *primitive-expand-table*
             'fluid-ref
             (case-lambda