fix up contract test suites

original commit: 8afeed8c663242159ac08ac043ccf860779ddd91

collects/mzlib/contract.rkt

@@ -72,9 +72,3 @@
  (all-from-out racket/contract/private/prop
                racket/contract/private/blame))
 
-
-;; copied here because not provided by racket/contract anymore
-(define (flat-contract/predicate? pred)
-  (or (flat-contract? pred)
-      (and (procedure? pred)
-           (procedure-arity-includes? pred 1))))

collects/mzlib/private/contract-struct.rkt

@@ -66,7 +66,7 @@
                   ...
                   [ctc-name-x (contract-name ctc-x)]
                   ...)
-              (build-flat-contract
+              (flat-named-contract
                (build-compound-type-name 'struct/c 'struct-name ctc-x ...)
                (λ (val)
                  (and (predicate-id val)