Revert D21870844: Create lazy_dyndeps to avoid caffe2 import costs.
Test Plan: revert-hammer
Differential Revision:
D21870844 (https://github.com/pytorch/pytorch/commit/07fd5f8ff992dddf4f3b0c286af9f7a3b53b617c)
Original commit changeset: 3f65fedb65bb
fbshipit-source-id: 4f661072d72486a9c14711e368247b3d30e28af9
