units: Fix mistake in 86bb85931d that could cause compile-time failures

Specifically, if a contracted binding was applied as a function inside
another contract, it would lead to a syntax error.

pkgs/racket-test/tests/units/test-unit.rkt

@@ -2276,3 +2276,30 @@
 
       (define result (foo 1 2 3))))
   (test 7 (dynamic-require ''m 'result)))
+
+;; ----------------------------------------
+;; Contracts that use other contracted bindings work when exporting through define-values/invoke-unit
+
+(parameterize ([current-namespace (make-base-namespace)])
+  (eval
+   '(module m racket/base
+      (require racket/contract
+               racket/unit)
+
+      (provide g)
+
+      (define-signature a^
+        [(contracted
+          [f (-> integer? contract?)]
+          [g (f 10)])])
+
+      (define-unit a@
+        (import)
+        (export a^)
+        (define (f x) (>=/c x))
+        (define g 11))
+
+      (define-values/invoke-unit a@
+        (import)
+        (export a^))))
+  (test 11 (dynamic-require ''m 'g)))

racket/collects/racket/private/unit-utils.rkt

@@ -51,10 +51,12 @@
                               member-table
                               i)))]
               [(x . y)
-               (quote-syntax
-                (#,(add-ctc i (bound-identifier-mapping-get
-                               member-table
-                               i)) . y))])))])))
+               (quasisyntax
+                (#,(quote-syntax
+                    #,(add-ctc i (bound-identifier-mapping-get
+                                  member-table
+                                  i)))
+                 . y))])))])))
 
 (define-syntax (unit-export stx)
   (syntax-case stx ()