data/gvector: fixed typo in constructor

Merge to 5.0.2
(cherry picked from commit 24297a793f)

collects/data/gvector.rkt

@@ -7,7 +7,7 @@
          racket/vector)
 
 (define (make-gvector #:capacity [capacity 10])
-  (make-gvector (make-vector capacity #f) 0))
+  (gvector (make-vector capacity #f) 0))
 
 (define gvector*
   (let ([gvector