XFail TestIRInterpreter on Windows

There's an open bug with calling functions in the inferior.  And Windows doesn't have the POSIX function getpid().

Differential Revision: http://reviews.llvm.org/D19626

llvm-svn: 267800

lldb/packages/Python/lldbsuite/test/expression_command/ir-interpreter/TestIRInterpreter.py

@@ -38,6 +38,7 @@ class IRInterpreterTestCase(TestBase):
         self.runCmd("run", RUN_SUCCEEDED)
 
     @add_test_categories(['pyapi'])
+    @expectedFailureAll(oslist=['windows'], bugnumber="21765")  # getpid() is POSIX, among other problems, see bug
     def test_ir_interpreter(self):
         self.build_and_run()