With this patch we can now gimplify all of libgcc without ICEing.  The
library isn't built, of course, as we still do not generate any code,
but at least we can gimplify all of it.

Aldy, Chris, we should add this as another test whenever we test
patches.  Make sure that we can continue going through libgcc and
gimple.exp.

Will commit as soon as I regain connectivity to gcc.gnu.org (not sure if
it's a local problem, as this machine is having issues with some other
sites as well).