Checking same object files produced

Given that the only #defines this code should be altering are those related to multiple-inclusion guards, I think we could describe any such ordering changes as a compiler bug. That is not to say that no such bugs exist, but it is likely that they'd also lead to inconsistent code generation when faced with identical output, and cause failures in GCC bootstrap comparison. (This has happened before, e.g. with optimizations depending on the ordering of pieces of compiler state in hash tables -- the infamous 'hashing by
address' bug class -- and that sort of thing.)