XFail TestIRInterpreter on Windows

[amccarth]

Summary

Test relies on a POSIX-only function getpid(), so the expression on Windows gets an undefined symbol. If you substitute _getpid(), the interpreter complains that it uses an opcode it doesn't support.

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

def build_and_run(self):
 
         self.runCmd("file a.out", CURRENT_EXECUTABLE_SET)
 
         lldbutil.run_break_set_by_file_and_line (self, "main.c", self.line, num_expected_locations=1, loc_exact=False)
 
         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()
 
         options = lldb.SBExpressionOptions()
         options.SetLanguage(lldb.eLanguageTypeC_plus_plus)
 
         set_up_expressions = ["int $i = 9", "int $j = 3", "int $k = 5"]