libshm retry on EINTR (#15964)
Summary:
fixes https://github.com/pytorch/pytorch/issues/14314
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15964
Differential Revision: D13639034
Pulled By: soumith
fbshipit-source-id: 44592762aa46982e5d3616d55b5666a2c2ce9105
