Revert D33892443: use irange for caffe2/aten directory
Test Plan: revert-hammer
Differential Revision:
D33892443 (https://github.com/pytorch/pytorch/commit/10cc66bc78adec0fa0af9c6d3de8475f98f9fe58)
Original commit changeset: eb76a3b39e6b
Original Phabricator Diff: D33892443 (https://github.com/pytorch/pytorch/commit/10cc66bc78adec0fa0af9c6d3de8475f98f9fe58)
fbshipit-source-id: 1072520eea5cae121b6dc82403d6679f9c768e3e
(cherry picked from commit b3dbef5e63b6afb50be10e75f8e5a2f69b5a8053)
