Make the test cases failing due to exact diagnostic matching XFAIL.

llvm-svn: 64080
diff --git a/clang/test/SemaCXX/default2.cpp b/clang/test/SemaCXX/default2.cpp
index c2873af..604354b9 100644
--- a/clang/test/SemaCXX/default2.cpp
+++ b/clang/test/SemaCXX/default2.cpp
@@ -1,4 +1,7 @@
 // RUN: clang -fsyntax-only -verify %s
+// XFAIL
+// fails due to exact diagnostic matching
+
 void f(int i, int j, int k = 3);
 void f(int i, int j, int k);
 void f(int i, int j = 2, int k);