Enable py::ellipsis on Python 2

Author: YannickJadoul

include/pybind11/pytypes.h

@@ -736,9 +736,7 @@ inline bool PyIterable_Check(PyObject *obj) {
 }
 
 inline bool PyNone_Check(PyObject *o) { return o == Py_None; }
-#if PY_MAJOR_VERSION >= 3
 inline bool PyEllipsis_Check(PyObject *o) { return o == Py_Ellipsis; }
-#endif
 
 inline bool PyUnicode_Check_Permissive(PyObject *o) { return PyUnicode_Check(o) || PYBIND11_BYTES_CHECK(o); }
 
@@ -1020,13 +1018,11 @@ class none : public object {
     none() : object(Py_None, borrowed_t{}) { }
 };
 
-#if PY_MAJOR_VERSION >= 3
 class ellipsis : public object {
 public:
     PYBIND11_OBJECT(ellipsis, object, detail::PyEllipsis_Check)
     ellipsis() : object(Py_Ellipsis, borrowed_t{}) { }
 };
-#endif
 
 class bool_ : public object {
 public: