Improve C macro guard: __Pyx_GetAttr() should be optimised exactly iff...

Improve C macro guard: __Pyx_GetAttr() should be optimised exactly iff __Pyx_PyObject_GetAttrStr() is also optimised.

Cython/Utility/ObjectHandling.c

@@ -1064,7 +1064,7 @@ static CYTHON_INLINE PyObject *__Pyx_GetAttr(PyObject *, PyObject *); /*proto*/
 //@requires: PyObjectGetAttrStr
 
 static CYTHON_INLINE PyObject *__Pyx_GetAttr(PyObject *o, PyObject *n) {
-#if CYTHON_COMPILING_IN_CPYTHON
+#if CYTHON_USE_TYPE_SLOTS
 #if PY_MAJOR_VERSION >= 3
     if (likely(PyUnicode_Check(n)))
 #else