XFAIL tests that try to call a function in the inferior.

llvm.org/pr21765

llvm-svn: 247456
diff --git a/lldb/test/expression_command/call-function/TestCallStdStringFunction.py b/lldb/test/expression_command/call-function/TestCallStdStringFunction.py
index c36577a..d39b943 100644
--- a/lldb/test/expression_command/call-function/TestCallStdStringFunction.py
+++ b/lldb/test/expression_command/call-function/TestCallStdStringFunction.py
@@ -30,6 +30,7 @@
     @expectedFailureFreeBSD('llvm.org/pr17807') # Fails on FreeBSD buildbot
     @expectedFailureIcc # llvm.org/pr14437, fails with ICC 13.1
     @expectedFailureDarwin(16361880) # <rdar://problem/16361880>, we get the result correctly, but fail to invoke the Summary formatter.
+    @expectedFailureWindows("llvm.org/pr21765")
     def test_with_dwarf(self):
         """Test calling std::String member function."""
         self.buildDwarf()