Prepare for using MS ABI by default for Win32: update CodeGenCXX tests

llvm-svn: 197281
diff --git a/clang/test/CodeGenCXX/global-llvm-constant.cpp b/clang/test/CodeGenCXX/global-llvm-constant.cpp
index 2bd43b9..6e202a7 100644
--- a/clang/test/CodeGenCXX/global-llvm-constant.cpp
+++ b/clang/test/CodeGenCXX/global-llvm-constant.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -emit-llvm -cxx-abi itanium -o - %s | FileCheck %s
 
 struct A {
   A() { x = 10; }