Skip coro test under the clang libstdcpp combination.

Author: adrian-prantl

lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/coroutine_handle/TestCoroutineHandle.py

@@ -75,6 +75,7 @@ def do_test(self, stdlib_type):
             ])
 
     @add_test_categories(["libstdcxx"])
+    @skipIf(compiler="clang")
     def test_libstdcpp(self):
         self.do_test(USE_LIBSTDCPP)