hopefully sate the clang self host build, which is apparently

instantiating some folding set stuff that GCC isn't, requiring 
some types to not be incomplete.

I don't know if clang is right or wrong, but unbreaking the
bot is goodness.  Here's the broken build:
http://google1.osuosl.org:8011/builders/clang-x86_64-darwin10-selfhost/builds/1813/steps/compile.llvm.stage2/logs/stdio

llvm-svn: 100418