[flang] [llvm] [Flang][FlangRT][Runtime] Add RT_OFFLOAD_API_GROUP_BEGIN to missing symbols on AMDGPU (PR #147612)

[via llvm-commits]

agozillon wrote:

> > I'd personally prefer to keep it as close to OpenMP standard acceptable as possible
> 
> I second this. Let's keep this PR as-is.

Sounds good! :-) 

> It would be worth "fixing" clang to apply `declare target` to explicit instantiations, but I am not sure who can do this.

It would indeed, I am unfortunately not the best person to do it I think unfortunately, aware of how it works in Flang, but not Clang as of yet... but I can bring it up internally and maybe someone will have the bandwidth to look at it. 

Thank you very much for the review @vzakhari 


https://github.com/llvm/llvm-project/pull/147612