Fix a layering violation introduced in r177705.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177922 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Basic/OpenMPKinds.cpp b/lib/Basic/OpenMPKinds.cpp
index 24d15ff..835908d 100644
--- a/lib/Basic/OpenMPKinds.cpp
+++ b/lib/Basic/OpenMPKinds.cpp
@@ -13,7 +13,7 @@
 
 #include "clang/Basic/OpenMPKinds.h"
 #include "clang/Basic/IdentifierTable.h"
-#include "clang/Lex/Token.h"
+#include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Support/ErrorHandling.h"
 #include <cassert>