Overwrite with `ln` if libc10.so already exists (#58243)
Summary:
This should fix the issue noted in https://github.com/pytorch/pytorch/pull/57622#issuecomment-840612300 and demonstrated in [this run](https://github.com/pytorch/pytorch/runs/2566809365). Please review this PR carefully, because I do not know enough context to know whether this is the right thing to do.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/58243
Test Plan: n/a
Reviewed By: walterddr
Differential Revision: D28414358
Pulled By: samestep
fbshipit-source-id: 0eb1c598f353ebac7f0a85c290be6fce4e00b6d5
