[llvm] r280740 - Fix ItaniumDemangle.cpp build with MSVC 2013

[Rafael Espíndola via llvm-commits]

On 6 September 2016 at 15:39, Reid Kleckner via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
> Author: rnk
> Date: Tue Sep  6 14:39:56 2016
> New Revision: 280740
>
> URL: http://llvm.org/viewvc/llvm-project?rev=280740&view=rev
> Log:
> Fix ItaniumDemangle.cpp build with MSVC 2013

Thanks and sorry! Somehow I missed this part when rebasing my patch.

Unfortunately we cannot use Compiler.h in here, since this library
should not depend on Support. But thanks a lot for the pointer, the
patch I was about to commit just deleted the custom allocator
completely. Given that the definition of ALIGNAS and CONSTEXPR are
fairly simple I will just try duplicating them.

Cheers,
Rafael