Stop binding std_single and var_single from TH; they aren't used anymore.
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/29951
Test Plan: Imported from OSS
Differential Revision: D18548057
Pulled By: gchanan
fbshipit-source-id: 0143f694517fa8229e53bd2bc636501804a3f80b
