[lld] [lld]Fix PGO Early Exit (PR #100555)

[Fangrui Song via llvm-commits]

MaskRay wrote:

lld currently doesn't use `target_compile_definitions`, so I am nervous that this adds a special case.
Perhaps I can try to use the fork model as mold does.

https://github.com/llvm/llvm-project/pull/100555