libcxx: Use vcruntime declarations for typeinfo on Windows.

We need to use the vcruntime declarations on Windows to avoid an
ODR violation involving rtti.obj, which provides the definition of
the runtime function implementing dynamic_cast and depends on the
vcruntime implementations of bad_cast and bad_typeid.

Differential Revision: https://reviews.llvm.org/D42220

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@323491 91177308-0d34-0410-b5e6-96231b3b80d8

include/typeinfo

@@ -69,6 +69,10 @@ public:
 #pragma GCC system_header
 #endif
 
+#if defined(_LIBCPP_ABI_MICROSOFT) && !defined(_LIBCPP_NO_VCRUNTIME)
+#include <vcruntime_typeinfo.h>
+#else
+
 #if !defined(_LIBCPP_ABI_MICROSOFT)
 #if defined(_LIBCPP_NONUNIQUE_RTTI_BIT)
 #define _LIBCPP_HAS_NONUNIQUE_TYPEINFO
@@ -219,6 +223,8 @@ public:
 
 }  // std
 
+#endif // defined(_LIBCPP_ABI_MICROSOFT) && !defined(_LIBCPP_NO_VCRUNTIME)
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 _LIBCPP_NORETURN inline _LIBCPP_ALWAYS_INLINE
 void __throw_bad_cast()