Revert "torch.special.gamma (#78904)"
This reverts commit f563f25efd6226d1a4f21cd8340b2b0380abac04.
Reverted https://github.com/pytorch/pytorch/pull/78904 on behalf of https://github.com/suo due to This PR appears to have broken mac tests on master https://hud.pytorch.org/pytorch/pytorch/commit/f563f25efd6226d1a4f21cd8340b2b0380abac04
