acl: Fix GetObjectACL xml parsing (#1598)

A recent change introduced a regression in parsing Object ACL S3 API.

This issue is not detected by minio-go functional tests since CI only
runs it against MinIO where Object ACL is unsupported.

Fix the regression and allow short testing of ObjectACL since MinIO
supports a small subset of the spec.

api-get-object-acl.go

@@ -47,8 +47,9 @@ type AccessControlList struct {
 }
 
 type accessControlPolicy struct {
-	Owner
-	AccessControlList
+	XMLName           xml.Name `xml:"AccessControlPolicy"`
+	Owner             Owner
+	AccessControlList AccessControlList
 }
 
 // GetObjectACL get object ACLs

functional_tests.go

@@ -11430,12 +11430,6 @@ func testGetObjectACLContext() {
 	// Seed random based on current time.
 	rand.Seed(time.Now().Unix())
 
-	// skipping region functional tests for non s3 runs
-	if os.Getenv(serverEndpoint) != "s3.amazonaws.com" {
-		ignoredLog(testName, function, args, startTime, "Skipped region functional tests for non s3 runs").Info()
-		return
-	}
-
 	// Instantiate new minio client object.
 	c, err := minio.New(os.Getenv(serverEndpoint),
 		&minio.Options{
@@ -11512,6 +11506,17 @@ func testGetObjectACLContext() {
 		return
 	}
 
+	// Do a very limited testing if this is not AWS S3
+	if os.Getenv(serverEndpoint) != "s3.amazonaws.com" {
+		if s[0] != "private" {
+			logError(testName, function, args, startTime, "", "GetObjectACL fail \"X-Amz-Acl\" expected \"private\" but got"+fmt.Sprintf("%q", s[0]), nil)
+			return
+		}
+
+		successLogger(testName, function, args, startTime).Info()
+		return
+	}
+
 	if s[0] != "public-read-write" {
 		logError(testName, function, args, startTime, "", "GetObjectACL fail \"X-Amz-Acl\" expected \"public-read-write\" but got"+fmt.Sprintf("%q", s[0]), nil)
 		return
@@ -12111,6 +12116,7 @@ func main() {
 		// Default to KMS tests.
 		kms = true
 	}
+
 	// execute tests
 	if isFullMode() {
 		testMakeBucketErrorV2()