Add meta support for _adaptive_avg_pool2d_backward (#86359) (#87074)
This reverts commit 3edf79dc03193c98b665d62231fe69a10dfab1fa.
Reland of https://github.com/pytorch/pytorch/pull/86359
Pull Request resolved: https://github.com/pytorch/pytorch/pull/87074
Approved by: https://github.com/ezyang
