[clang] [LinkerWrapper] Always pass `-flto` if the linker supports it (PR #102972)

[Joseph Huber via cfe-commits]

jhuber6 wrote:

I'm very familiar with that error message, it's https://github.com/llvm/llvm-project/issues/64863. I guess I should just manually pass the optimization level at `O2` for now.

https://github.com/llvm/llvm-project/pull/102972