Remove MSVC workaround for AlignedCharArray (NFC)

[mehdi_amini]

Summary

The comment only mentioned "old version of MSVC".

[mehdi_amini]

(If someone can confirm it works on the current MSVC 2015)

[bkramer]

I tried this recently and it still doesn't work (rL284738)

[mehdi_amini]

Thanks bkramer! Let's just improve the comment then?

[bkramer]

Thanks! And sorry for missing this in my revert.

[rnk]

This whole type is basically a lie, though. 32-bit MSVC only ever aligns objects passed by value to 4 bytes. MSVC will issue an error if you try to pass something with __declspec(align) by value. This ifdef effectively works around that diagnostic, but fails to accomplish the goal of alignment.

If we ever depend on the alignment of these objects when they are passed by value, we are screwed. The only thing that saves us today is that we don't often pass highly aligned things by value.

So, there is more work to do here.

llvm/include/llvm/Support/AlignOf.h

 
 namespace llvm {
 
 /// \struct AlignedCharArray
 /// \brief Helper for building an aligned character array type.
 ///
 /// This template is used to explicitly build up a collection of aligned
 /// character array types. We have to build these up using a macro and explicit
-/// specialization to cope with old versions of MSVC where only an
+/// specialization to cope with MSVC (at least till 2015) where only an
 /// integer literal can be used to specify an alignment constraint. Once built
 /// up here, we can then begin to indirect between these using normal C++
 /// template parameters.
 
 // MSVC requires special handling here.
 #ifndef _MSC_VER
 
 template<std::size_t Alignment, std::size_t Size>