cs: fix interactio of unsafe capture and barriers

Fix `unsafe-call-with-composable-continuation/no-wind` so that it's
not blocked by a barrier, since it's supposed to have thread-like
capturing ability.

Closes #3696

pkgs/racket-test-core/tests/racket/try-atomic.rkt

@@ -19,3 +19,19 @@
  'no)
 
 (check done? #t)
+
+(set! done? #f)
+
+(check
+ (call-as-nonatomic-retry-point
+  (lambda ()
+    (try-atomic
+     (lambda ()
+       (call-with-continuation-barrier
+        (lambda ()
+          (sync/timeout 0.25 ch)))
+       (set! done? #t))
+     'barrier)))
+ 'barrier)
+
+(check done? #t)

racket/src/cs/rumble/control.ss

@@ -526,7 +526,7 @@
      (|#%app|
       p
       (make-composable-continuation
-       (extract-metacontinuation 'call-with-composable-continuation (strip-impersonator tag) #f)
+       (extract-metacontinuation 'call-with-composable-continuation (strip-impersonator tag) (not wind?))
        k
        (current-winders)
        (current-mark-stack)