Propagate information on torch_shm_manager execl failure to parent process (#57310)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/57310
If we fail to exec `torch_shm_manager`, write an appropriate error message to stdout so that the parent process can have some context on the failure.
Reviewed By: ejguan
Differential Revision: D28047917
fbshipit-source-id: 68bf357df7a6b318c036f4f62cbb428a62cb139e
