Remove with-fluids; replaced by with-fluid* and inlined push-fluid primops

* libguile/vm-i-system.c (push-fluid, pop-fluid):
* doc/ref/vm.texi (Dynamic Environment Instructions): Rename wind-fluids
  to push-fluid, and unwind-fluids to pop-fluid.  They now only work on
  one fluid binding at a time.

* module/ice-9/boot-9.scm (with-fluid*): Implement in Scheme in terms of
  primcalls to push-fluid and pop-fluid.
  (custom-throw-handler, catch, with-throw-handler): Use with-fluid*
  instead of with-fluids, as with-fluids is no longer available before
  psyntax is loaded.
  (with-fluids): Define in Scheme in terms of with-fluid*.

* libguile/fluids.c (scm_with_fluid): Rename from scm_with_fluids, and
  don't expose to Scheme.

* libguile/eval.c (eval): Remove SCM_M_WITH_FLUIDS case.
* libguile/expand.c (expand_with_fluids): Remove with-fluids syntax.
  (DYNLET): Remove, no longer defining dynlet in the %expanded-vtables.
* libguile/expand.h: Remove dynlet definitions.
* module/ice-9/eval.scm (primitive-eval): Remove with-fluids case.
* libguile/memoize.c (do_push_fluid, do_pop_fluid): New primitive
  helpers, like wind and unwind.
  (memoize): Memoize wind and unwind primcalls.  Don't memoize dynlet to
  with-fluids.
  (scm_init_memoize): Initialize push_fluid and pop_fluid here.
* libguile/memoize.h (SCM_M_WITH_FLUIDS): Remove definition.

* module/ice-9/psyntax.scm (build-dynlet): Remove; this just supported
  with-fluids, which is now defined in boot-9.
* module/ice-9/psyntax-pp.scm: Regenerate.

* doc/ref/compiler.texi (Tree-IL):
* module/language/tree-il.scm:
* module/language/tree-il/analyze.scm:
* module/language/tree-il/canonicalize.scm:
* module/language/tree-il/compile-glil.scm:
* module/language/tree-il/cse.scm:
* module/language/tree-il/debug.scm:
* module/language/tree-il/effects.scm: Remove <dynlet>.  Add cases for
  primcalls to push-fluid and pop-fluid in compile-glil.scm and
  effects.scm.

* module/language/tree-il/peval.scm (peval): Factor out
  with-temporaries; probably a bad idea, but works for now.  Factor out
  make-begin0 (a better idea).  Inline primcalls to with-fluid*, and
  remove dynlet cases.

* module/language/tree-il/primitives.scm (*interesting-primitive-names*):
  Add with-fluid*.

module/language/scheme/decompile-tree-il.scm

@@ -432,12 +432,6 @@
          `(call-with-values (lambda () ,@(recurse-body exp))
             ,(recurse (make-lambda #f '() body))))
 
-        ((<dynlet> fluids vals body)
-         `(with-fluids ,(map list
-                             (map recurse fluids)
-                             (map recurse vals))
-            ,@(recurse-body body)))
-
         ((<prompt> tag body handler)
          `(call-with-prompt
            ,(recurse tag)
@@ -750,12 +744,6 @@
              (primitive 'call-with-values)
              (recurse exp) (recurse body))
 
-            ((<dynlet> fluids vals body)
-             (primitive 'with-fluids)
-             (for-each recurse fluids)
-             (for-each recurse vals)
-             (recurse body))
-
             ((<prompt> tag body handler)
              (primitive 'call-with-prompt)
              (primitive 'lambda)