Added x-minio-replication-actual-object-size to allowed headers (#1946

)

Need to send actual object size while replicating a multipart
object as parts would be replicated as is with their encrypted
content and content length. Later, at target, while creating xl.meta
for the completed object, we need the actual object size to be set as
`X-Minio-Internal-actual-size`

Signed-off-by: Shubhendu Ram Tripathi <shubhendu@minio.io>

utils.go

@@ -517,6 +517,7 @@ var supportedReplicationEncryptionHeaders = map[string]bool{
 	"x-minio-replication-server-side-encryption-seal-algorithm": true,
 	"x-minio-replication-server-side-encryption-iv":             true,
 	"x-minio-replication-encrypted-multipart":                   true,
+	"x-minio-replication-actual-object-size":                    true,
 	// Add more supported headers here.
 	// Must be lower case.
 }