Make one_hot non-differentiable. (#19524)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/19524
ghimport-source-id: ceda3ad43471242ebbd272a21de11731c7d8bef6
Differential Revision: D15021417
Pulled By: gchanan
fbshipit-source-id: 65d1f17a32f81f47dba5e58e343d0b7b828e1d51
