[filetransfer] Set the status to error in setException()

FileTransfer would previously not change the status, even though an
exception has been set, leading users to believe that the transfer is
still ongoing, when it is not.

smack-extensions/src/main/java/org/jivesoftware/smackx/filetransfer/FileTransfer.java

@@ -183,6 +183,10 @@ public abstract class FileTransfer {
 
     protected void setException(Exception exception) {
         this.exception = exception;
+        Status currentStatus = getStatus();
+        if (currentStatus != Status.error) {
+            updateStatus(currentStatus, Status.error);
+        }
     }
 
     protected void setStatus(Status status) {