Hello,
Thank you for your message. I'm afraid I can't find any evidence in other dictionaries that this is the case, and even everyone's favourite search engine just shows me results for "rotary clotheslines" (it obviously knows what I mean, but I can't see the actual word "whirligig" anywhere among the results).
Could this be a regional thing? If you can supply some evidence or more information, I'll gladly consider it.