Revert "Move c10/util math helper headers into torch/headeronly (#194673)"

This reverts commit 14780aaa3ad92d063f64fde1a0e017239164e97b.

Reverted https://github.com/pytorch/pytorch/pull/194673 on behalf of https://github.com/pytorch-auto-revert due to Reverted automatically by pytorch's autorevert, to avoid this behaviour add the tag autorevert: disable ([comment](https://github.com/pytorch/pytorch/pull/194673#issuecomment-5419897798))