[lldb] XFAIL TestForwardDeclaration.test_debug_names on windows

Before 539b47c9 this test was not actually using the debug_names section
because the -gdwarf added by Makefile.rules on windows overrode the
-gdwarf-5 flag from CFLAGS_EXTRAS. Now that -gdwarf-5 is respected, the
test is failing.

lldb/test/API/lang/c/forward/TestForwardDeclaration.py

@@ -59,6 +59,7 @@ class ForwardDeclarationTestCase(TestBase):
     @skipIfDarwin
     @skipIf(compiler=no_match("clang"))
     @skipIf(compiler_version=["<", "7.0"])
+    @expectedFailureAll(oslist=["windows"])
     def test_debug_names(self):
         """Test that we are able to find complete types when using DWARF v5
         accelerator tables"""