Fix LBFGS issue (#16167)
Summary:
Resolves #15923 where LBFGS threw "Error: a leaf Variable that requires grad has been used in an in-place operation."
Pull Request resolved: https://github.com/pytorch/pytorch/pull/16167
Differential Revision: D13745822
Pulled By: soumith
fbshipit-source-id: 7d1d0511d06838c0c6f4c8a6b53cf15193283059
