supported by specific versions of GCC.
It is left in place in case anyone wants to updated it for GCC 3.4 or
re-use it for earlier versions of GCC where it works.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@17324 91177308-0d34-0410-b5e6-96231b3b80d8