This fixes compatibility with llvm after r273499 and r273595, when LLVM started to emit PLT relocations even in static mode causing a regression.
If we're going to specifically comment on LLVM's behavior here, I think it is worth mentioning that GNU ld does the same thing. The comments should explain what the linker is doing, and why (e.g., support directly resolving PLT-relative relocations when statically linking).
Also, this will need a test case.
Does this say that this is not exactly what we are supposed to do to relocations of this type? If so, please state that first and what we should actually do (what type should actually be returned from this function?).
Sorry, why are you pinging the review? It is approved so you can commit it. Is the issue that you don't have commit access and need someone to commit it? If so, you should state that rather than just pinging the patch.