[llvm] [Offload] Lazily initialize platforms in the Offloading API (PR #227084)

[Alex Duran via llvm-commits]

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adurang wrote:

could we maybe store the error and return it at olShutdown? At least, we should print some kind of (debug) message. Otherwise the error gets lost which might make debugging hard.

https://github.com/llvm/llvm-project/pull/227084