speed up Python long integer operations in Python 2.7

This it less important than in Py3 as most optimisable cases are already covered by PyInt, but long objects might still pop up arbitrarily in Py2, so it might be worth it.

CHANGES.rst

@@ -36,6 +36,8 @@ Features added
 
 * Binary lshift operations with small constant Python integers are faster.
 
+* Some integer operations on Python long objects are faster in Python 2.7.
+
 Bugs fixed
 ----------
 

Cython/Utility/Optimize.c

@@ -604,7 +604,7 @@ static PyObject* __Pyx_PyInt_{{op}}{{order}}(PyObject *op1, PyObject *op2, CYTHO
     }
     #endif
 
-    #if CYTHON_USE_PYLONG_INTERNALS && PY_MAJOR_VERSION >= 3
+    #if CYTHON_USE_PYLONG_INTERNALS
     if (likely(PyLong_CheckExact({{pyval}}))) {
         const long {{'a' if order == 'CObj' else 'b'}} = intval;
         long {{ival}}{{if op not in ('Eq', 'Ne')}}, x{{endif}};
@@ -787,7 +787,7 @@ static PyObject* __Pyx_PyFloat_{{op}}{{order}}(PyObject *op1, PyObject *op2, dou
     #endif
 
     if (likely(PyLong_CheckExact({{pyval}}))) {
-        #if CYTHON_USE_PYLONG_INTERNALS && PY_MAJOR_VERSION >= 3
+        #if CYTHON_USE_PYLONG_INTERNALS
         const digit* digits = ((PyLongObject*){{pyval}})->ob_digit;
         const Py_ssize_t size = Py_SIZE({{pyval}});
         switch (size) {