[clang] [llvm] [OpenMP] Remove dependency on `libffi` from offloading runtime (PR #91264)

[Joseph Huber via cfe-commits]

jhuber6 wrote:

I hacked around it in the runtime itself. Obviously this is very OpenMP specific behavior but so was the old method. Passes all tests now.

https://github.com/llvm/llvm-project/pull/91264