Fix ldflags string for HIPExtensions (#38047)
Summary:
This pull request adds a check for ROCm environment and skips adding CUDA specific flags for the scenario when a pytorch extension is built on ROCm.
ezyang jeffdaily
Pull Request resolved: https://github.com/pytorch/pytorch/pull/38047
Differential Revision: D21470507
Pulled By: ezyang
fbshipit-source-id: 5af2d7235e306c7aa9a5f7fc8760025417383069
