Stop using PyNone_Type for Python 2.7

Author: mrkn

lib/pycall/libpython.rb

@@ -175,12 +175,6 @@ def self.Py_None
 
     attach_variable :PyType_Type, PyTypeObjectStruct
 
-    if libpython.find_variable('_PyNone_Type')
-      attach_variable :PyNone_Type, :_PyNone_Type, PyTypeObjectStruct
-    else
-      attach_variable :PyNone_Type, PyTypeObjectStruct
-    end
-
     if libpython.find_variable('PyInt_Type')
       has_PyInt_Type = true
       attach_variable :PyInt_Type, PyTypeObjectStruct

spec/pycall/pyptr_spec.rb

@@ -59,11 +59,11 @@ module PyCall
       end
 
       it 'works for Python type objects' do
-        pynone_type = PyPtr.incref(PyPtr.new(LibPython.PyNone_Type.to_ptr.address))
+        pytype_type = PyPtr.incref(PyPtr.new(LibPython.PyType_Type.to_ptr.address))
         pylong_type = PyPtr.incref(PyPtr.new(LibPython.PyLong_Type.to_ptr.address))
 
-        expect(PyPtr::None.kind_of?(pynone_type)).to eq(true)
-        expect(PyPtr::None.kind_of?(pylong_type)).to eq(false)
+        expect(pylong_type.kind_of?(pytype_type)).to eq(true)
+        expect(pylong_type.kind_of?(pylong_type)).to eq(false)
 
         expect { PyPtr::None.kind_of?(PyPtr::None) }.to raise_error(TypeError)
       end