[llvm] [Offload] Do not link every target for JIT (PR #92013)

[Shilei Tian via llvm-commits]

shiltian wrote:

The problem with this patch is, you will end up with undefined symbols if you just link the corresponding target. For example, the LLVM was built with target AMDGPU and NVPTX. So when `PluginCommon` is compiled, the code for initializing both are enabled. However, when you eventually link AMDGPU plugin, you only link against AMDGPU. That will leave those NVPTX initialization code undefined symbols.

https://github.com/llvm/llvm-project/pull/92013