Fix for PyNone_Type

Author: mrkn

lib/pycall/libpython.rb

@@ -174,7 +174,12 @@ def self.Py_None
     end
 
     attach_variable :PyType_Type, PyTypeObjectStruct
-    attach_variable :_PyNone_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

spec/pycall/pyptr_spec.rb

@@ -59,7 +59,7 @@ module PyCall
       end
 
       it 'works for Python type objects' do
-        pynone_type = PyPtr.incref(PyPtr.new(LibPython._PyNone_Type.to_ptr.address))
+        pynone_type = PyPtr.incref(PyPtr.new(LibPython.PyNone_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)