TokenKinds: _Atomic isn't a keyword in MS mode

Summary:
This is needed to allow MSVC's <atomic> header to properly parse.
It uses _Atomic as a class-id.

Reviewers: rnk

Reviewed By: rnk

CC: cfe-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D2948

llvm-svn: 202901
diff --git a/clang/test/SemaCXX/MicrosoftCompatibility.cpp b/clang/test/SemaCXX/MicrosoftCompatibility.cpp
index a3b96da..fb7d975 100644
--- a/clang/test/SemaCXX/MicrosoftCompatibility.cpp
+++ b/clang/test/SemaCXX/MicrosoftCompatibility.cpp
@@ -3,6 +3,7 @@
 
 typedef unsigned short char16_t;
 typedef unsigned int char32_t;
+struct _Atomic {};
 
 typename decltype(3) a; // expected-warning {{expected a qualified name after 'typename'}}