Fix bug on empty GLOO_SOCKET_IFNAME_ENV (#68933)
Summary:
This PR is trying to fix the no device bug when user resets the `GLOO_SOCKET_IFNAME_ENV` with
```bash
export GLOO_SOCKET_IFNAME_ENV=
```
Thank you for your time on reviewing this PR :).
cc pietern mrshenli pritamdamania87 zhaojuanmao satgera rohan-varma gqchen aazzolini osalpekar jiayisuse SciPioneer H-Huang
Pull Request resolved: https://github.com/pytorch/pytorch/pull/68933
Reviewed By: soulitzer
Differential Revision: D32690633
Pulled By: mrshenli
fbshipit-source-id: f6df2b8b067d23cf1ec177c77cc592dc870bda72
