Fix libcxx MSVC C++17 redefinition of 'align_val_t'

Patch from 	charlieio@outlook.com

Reviewed as https://reviews.llvm.org/D42354

When the following command is used:

> clang-cl -std:c++17 -Iinclude\c++\v1 hello.cc c++.lib

An error occurred:

In file included from hello.cc:1:
In file included from include\c++\v1\iostream:38:
In file included from include\c++\v1\ios:216:
In file included from include\c++\v1\__locale:15:
In file included from include\c++\v1\string:477:
In file included from include\c++\v1\string_view:176:
In file included from include\c++\v1\__string:56:
In file included from include\c++\v1\algorithm:643:
In file included from include\c++\v1\memory:656:
include\c++\v1\new(165,29):  error: redefinition of 'align_val_t'
enum class _LIBCPP_ENUM_VIS align_val_t : size_t { };
                            ^
C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.12.25827\include\vcruntime_new.h(43,16):  note:
      previous definition is here
    enum class align_val_t : size_t {};
               ^
1 error generated.
vcruntime_new.h has defined align_val_t, libcxx need hide align_val_t.

This patch fixes that error.


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324853 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/new b/include/new
index 4e52750..27c248c 100644
--- a/include/new
+++ b/include/new
@@ -160,6 +160,7 @@
 
 #endif  // defined(_LIBCPP_BUILDING_NEW) || (_LIBCPP_STD_VER > 11)
 
+#if !defined(_LIBCPP_ABI_MICROSOFT) || defined(_LIBCPP_NO_VCRUNTIME)
 #if !defined(_LIBCPP_HAS_NO_ALIGNED_ALLOCATION) || _LIBCPP_STD_VER > 14
 #ifndef _LIBCPP_CXX03_LANG
 enum class _LIBCPP_ENUM_VIS align_val_t : size_t { };
@@ -167,6 +168,7 @@
 enum align_val_t { __zero = 0, __max = (size_t)-1 };
 #endif
 #endif
+#endif
 
 }  // std