[LTO] Appease buildbots take 3

This time I've found a linux box and checked it there. This test now passes.

Because I'd introduced an undefined reference in @bar, gold now returns an error. This doesn't matter for the test itself, because it also emits the remarks the test is checking for. But it does cause LIT to notice a nonzero return code which it faults on.

llvm-svn: 253454