[llvm] [Offload] Fix: Target JIT registers no backends when LLVM_LINK_LLVM_DYLIB=ON (PR #227370)

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sgasho wrote:

> Please reply to this message to confirm that you have read these policies, especially the LLVM AI Tool Use Policy, and that any AI tool usage has been noted in the PR description.

I read the policies and added the AI tool usage at the end of the PR description

https://github.com/llvm/llvm-project/pull/227370