gx update go-cid and fix code to use new Cid type

package.json

@@ -13,9 +13,9 @@
     },
     {
       "author": "whyrusleeping",
-      "hash": "QmZFbDTY9jfSBms2MchvYM9oYRbAF19K7Pby47yDBfpPrb",
+      "hash": "QmPSQnBKM9g7BaUcZCvswUJVscQ1ipjmwxN5PXCjkp9EQ7",
       "name": "go-cid",
-      "version": "0.8.0"
+      "version": "0.9.0"
     }
   ],
   "gxVersion": "0.12.1",

validate.go

@@ -48,7 +48,7 @@ func IsGoodHash(code uint64) bool {
 	return false
 }
 
-func ValidateCid(c *cid.Cid) error {
+func ValidateCid(c cid.Cid) error {
 	pref := c.Prefix()
 	if !IsGoodHash(pref.MhType) {
 		return ErrPossiblyInsecureHashFunction

validate_test.go

@@ -32,7 +32,7 @@ func TestValidateCids(t *testing.T) {
 
 	assertFalse(IsGoodHash(mh.BLAKE2B_MIN + 5))
 
-	mhcid := func(code uint64, length int) *cid.Cid {
+	mhcid := func(code uint64, length int) cid.Cid {
 		mhash, err := mh.Sum([]byte{}, code, length)
 		if err != nil {
 			t.Fatal(err)
@@ -41,7 +41,7 @@ func TestValidateCids(t *testing.T) {
 	}
 
 	cases := []struct {
-		cid *cid.Cid
+		cid cid.Cid
 		err error
 	}{
 		{mhcid(mh.SHA2_256, 32), nil},