[llvm] [offload] Fix link issues when LLVM_LINK_LLVM_DYLIB on (PR #106583)

[via llvm-commits]

macurtis-amd wrote:

> This is confusing, why would it be firing the constructors multiple times? If we link it statically then there should be no dynamic module. Are we somehow doing both?

Yes. That is what I observed. The `target_link_libraries` calls modified by this commit add the static libs. The dynamic `LLVM` lib also ends up in the list of libraries to link against.

LLVM provided functions such as `add_llvm_library` do the right thing and add either the `LLVM` dynamic lib or the provided static libs (see [llvm/cmake/modules/AddLLVM.cmake:741](https://github.com/llvm/llvm-project/blob/fab925651685505906416dca48469fd9f69ba39a/llvm/cmake/modules/AddLLVM.cmake#L741)).

It seems we run into trouble when doing things ourselves.

https://github.com/llvm/llvm-project/pull/106583