Remove unused capture in tensorpipe_agent.cpp (#37828)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/37828
Test Plan: Imported from OSS
Differential Revision: D21407942
Pulled By: mrshenli
fbshipit-source-id: 72c0cc36d6aa61d48c9108850f5e8ba1eb6a7507
