[llvm] [offload] Decouple PluginManager from the OpenMP offload policy handling (PR #208113)

[Ivan R. Ivanov via llvm-commits]

================
@@ -328,7 +328,7 @@ void *llvm_omp_target_dynamic_shared_alloc();
 void __tgt_register_requires(int64_t Flags);
 
 /// Initializes the runtime library.
----------------
ivanradanov wrote:

I would not classify it as an ABI change as this specific API is only used in the one test that I edit in this PR as far as I understand. The initialization goes through the `register_lib` calls which are generated by the compiler, so calls to `__tgt_rtl_{init,deinit}` should never appear in user's binaries (unless they decided to declare and call them themselves...? Which is something I do not think we support)

I was seeing this API as purely for testing.

I can still make a new API specifically for this is you prefer that.

(the commit that added them https://github.com/llvm/llvm-project/commit/ea174c09342275d6c6fec48fb846eaf28fae5b51 and a `git grep rtl_init` only hits these files here and not the compiler)

https://github.com/llvm/llvm-project/pull/208113