Fix tests for PyPy2

Author: vstinner

tests/test_pythoncapi_compat_cext.c

@@ -879,12 +879,17 @@ test_vectorcall_args_kwnames(PyObject *func_varargs)
     Py_ssize_t pos = 0;
     PyObject *key, *value;
     while (PyDict_Next(kwargs, &pos, &key, &value)) {
+#ifdef PYTHON3
         assert(PyUnicode_Check(key));
-        if (PyUnicode_Compare(key, key1) == 0) {
+#else
+        // CPython 2.7 creates PyUnicode keys, PyPy2 creates PyString keys
+        assert(PyString_Check(key) || PyUnicode_Check(key));
+#endif
+        if (PyObject_RichCompareBool(key, key1, Py_EQ)) {
             check_int(value, 4);
         }
         else {
-            assert(PyUnicode_Compare(key, key2) == 0);
+            assert(PyObject_RichCompareBool(key, key2, Py_EQ));
             check_int(value, 5);
         }
     }