Chris Jefferson found a defect in the C++0x working draft by trying to run...

Chris Jefferson found a defect in the C++0x working draft by trying to run libc++ against boost.  I've submitted an issue to the LWG, and this commit attempts to implement the proposed resolution of that defect report.  I'd point to the issue but it hasn't been put into the LWG list yet.  The title of the issue will be: Stage 2 accumulate incompatibilty

llvm-svn: 127303