From: Stan Shebs <shebs@apple.com>
It's hard for anybody outside Apple to reproduce on Darwin right now,
because you need an up-to-the-minute Tiger with all the trimmings,
but you could kludge up a similar situation by taking a standard x86
Linux config and defining a multilib with a -m codegen option that
produces code that can't possibly run on the CPU you're using to
build things. The tools are fine with building shlibs and even
executables for that -m option, but you can't run any of it until
you've moved to the right kind of CPU. (You might have to add code
to the little conftest programs to guarantee the exectime failure,
depending on the -m option you use.)