* Define HASH_NAMESPACE to `std' in the case of pre-3.0 GCC compilers
* Add comments to clarify the intent of all the #ifdef madness
* Add VIM directive to highlight files as C++
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@7903 91177308-0d34-0410-b5e6-96231b3b80d8