Revert "Disable pylong optimizations on 32-bit."

This reverts commit e4fcfa3b.

Cython/Utility/Optimize.c

@@ -606,13 +606,6 @@ static PyObject* __Pyx_PyInt_{{op}}{{order}}(PyObject *op1, PyObject *op2, CYTHO
     }
     #endif
 
-    {{if op == 'Lshift'}}
-    // Work around Github #1530.
-    if (sizeof(long) < 8) {
-        return PyNumber_Lshift(op1, op2);
-    }
-    {{endif}}
-
     #if CYTHON_USE_PYLONG_INTERNALS
     if (likely(PyLong_CheckExact({{pyval}}))) {
         const long {{'a' if order == 'CObj' else 'b'}} = intval;